Digital video signal record and playback device and method for selectively reproducing desired video information from an optical disk

ABSTRACT

A digital video signal record and playback device for recording on a recording medium a digital video signal coded by using a motion compensation prediction and an orthogonal transform and playing back data from the recording medium. In a data arrangement of a digital video signal, an I picture which can be independently represented in a picture is divided into n areas in the vertical direction, and the data is arranged from the front of one GOP in the unit of area by giving a priority to an area located at the center of the screen. A playback picture is outputted by playing back the I picture read from the recording medium in the unit of area unit. In the case where the whole I picture area cannot be read within a definite time, the area which cannot be read are interpolated by the use of the data of the preceding screen.

This application is a divisional of application Ser. No. 09/520,283,filed on Mar. 6, 2000 now U.S. Pat. No. 6,549,717, which is a divisionalof application Ser. No. 09/329,333, filed on Jun. 10, 1999 and issued asU.S. Pat. No. 6,134,382 on Oct. 17, 2000, which is a divisional ofapplication Ser. No. 08/877,875 filed on Jun. 18, 1997 and issued asU.S. Pat. No. 6,009,236 on Dec. 28, 1999, which is a continuation ofapplication Ser. No. 08/533,109 filed Sep. 25, 1995 and now abandoned,the entire contents of which are hereby incorporated by reference andfor which priority is claimed under 35 U.S.C. § 120; and thisapplication claims priority of Application No. 6-229620; 6-252098;6-272107 and 7-28277 filed in Japan on Sep. 26, 1994; Oct. 18, 1994;Nov. 7, 1994 and Feb. 16, 1995, respectively under 35 U.S.C. § 119.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to a digital video signal record andplayback device for recording and playing back a digital video signal,and more particularly to a digital video signal record and playbackdevice for recording and playing back on a medium such as an opticaldisc or the like, a digital video signal coded on the basis of a motioncompensation prediction and an orthogonal conversion.

2. Description of Related Art

FIG. 1 is a block circuit diagram of a conventional optical disc recordand playback device shown in the Japanese Patent Application Laid-OpenNo. HEI 4-114369 (1992). Referring to FIG. 1, reference numeral 201denotes an A/D converter for converting a video signal, an audio signalor the like into digital information. Reference numeral 202 denotes adata compressing circuit, 203 a frame sector converting circuit forconverting compressed data into sector data which is equal to integertimes of a frame cycle, 204 an error correction coder for adding theerror correction signal to sector data, 205 a modulator for modulatinginterference between codes in a recording medium into a predeterminedmodulation code to reduce the interference, 206 a laser driving circuitfor modulating laser light in accordance with a modulation code, and 207a laser output switch. Further, reference numeral 208 denotes an opticalhead for emitting laser light, 209 an actuator for tracking a light beamemitted from the optical head 208, 210 a traverse motor for sending theoptical head 208. 211 a disc motor for rotating an optical disc 212, 219a motor driving circuit, 220 a first control circuit and 221 a secondcontrol circuit. Further, reference numeral 213 denotes a playbackamplifier for amplifying a playback signal from the optical head 208.Reference numeral 214 denotes a demodulator for obtaining data from arecorded modulation signal, 215 an error correction decoder, 216 a framesector inverse converting circuit, 217 a data extending circuit forextending the compressed data, 218 a D/A converter for convertingextended data into, for example, an analog video signal and an audiosignal.

FIG. 2 is a block circuit diagram showing an inside structure of thedata compressing circuit 202 in FIG. 1. In FIG. 2, a digital videosignal inputted from the A/D converter 201 is inputted into a memorycircuit 301. A video signal 321 outputted from the memory circuit 301 isprovided as a first input of a subtracter 302 and a second input of amotion compensation predicting circuit 310. An output of the subtracter302 is inputted to a quantizer 304 via a DCT (discrete cosine transform)circuit 303. An output of the quantizer 304 is provided as an input of atransmission buffer 306 via a variable-length encoder 305. An output ofthe transmission buffer 306 is outputted to the frame sector convertingcircuit 203. In the meantime, an output of the quantizer 304 is inputtedto the inverse DCT circuit 308 via an inverse quantizer 307. An outputof the inverse DCT circuit 308 is provided as a first input of an adder309. An output 322 of the adder 309 is provided as a first input of amotion compensation predicting circuit 310. An output 323 of the motioncompensation predicting circuit 310 is provided as a second input of theadder 309 and a second input of the subtracter 302.

FIG. 3 is a block circuit diagram showing an inside structure of themotion compensation predicting circuit 310 in FIG. 2. In FIG. 3, theoutput 322 of the adder 309 is provided as an input terminal 401 a whilethe output 321 of the memory circuit 301 is provided as an inputterminal 401 b. The signal 322 inputted from the input terminal 401 a isinputted to a frame memory 404 a or a frame memory 404 b via a switch403. A reference picture outputted from the frame memory 404 a isprovided as a first input of a motion vector detecting circuit 405 a.The video signal 321 inputted from the input terminal 401 b is inputtedto a second input of the motion vector detecting circuit 405 a. Anoutput of the motion vector detecting circuit 405 a is inputted to aprediction mode selector 406. In the meantime, the reference pictureoutputted from the frame memory 404 b is provided as a first input of amotion vector detecting circuit 405 b. The video signal 321 inputtedfrom the input terminal 401 b is provided as the second input of theprediction mode selector 406. The video signal 321 inputted from theinput terminal 401 b is provided as a third input of the prediction modeselector 406. A zero signal is provided as a second input of a switch407. A second output of the prediction mode selector 406 is provided asa third input of the switch 407. The output 323 of the switch 407 isoutputted from a output terminal 402.

FIG. 4 is a block circuit diagram showing an inside structure of thedata extending circuit 217 in FIG. 1. In FIG. 4, the video signalinputted from the frame sector inverse converting circuit 216 isinputted to a reception buffer 501. An output from the reception buffer501 is inputted to a variable-length decoder 502, and the outputtherefrom is inversely quantized at an inverse quantizer 503. Then, theoutput is subjected to an inverse discrete cosine transform at aninverse DCT circuit 504. The output is provided as a first input of anadder 506. In the meantime, the output of the reception buffer 501 isprovided as a prediction data decoding circuit 505 while an output ofthe prediction data decoding circuit 505 is provided as a second outputof the adder 506. The output of the adder 506 is outputted to the D/Aconverter 218 via a memory circuit 507.

Next, operation of the device of FIG. 1 will be explained. As one highefficiency coding mode in the case of coding a video signal, there is ancoding algorithm for a MPEG (Moving Picture Expert Group) mode. This isa hybrid coding mode which combines an inter-frame prediction codingusing a motion compensation prediction and an intra-frame conversioncoding. This conventional example uses a data compressing circuit 202having a structure shown in FIG. 2 and adopts the aforementioned MPEGmode.

FIG. 5 shows a simplified data arrangement structure (layer structure)of MPEG mode. In FIG. 5, reference numeral 621 denotes a sequence layercomprising a group of pictures (hereinafter referred to as “GOP”)comprising a plurality of frame data items, 622 a GOP layer comprisingseveral pictures (screens), 623 a slice which divides one screen intoseveral blocks, 624 a slice layer which has several macroblocks, 625 amacroblock layer, 626 a block layer which includes 8 pixels×8 pixels.

This macroblock layer 625 is a block which includes a least unit of 8pixels×8 pixels, for example, in the MPEG mode. This block is a unit forperforming DCT. At this time, a total of 6 blocks, including adjacentfour Y signal blocks, one Cb block which corresponds to the Y signalblocks in position, and one Cr block are referred to as a macroblock. Aplurality of these macroblocks constitute a slice. In addition, themacroblocks constitute a minimum unit of a motion compensationprediction, and a motion vector for the motion compensation predictionis formed in macroblock units.

Subsequently, a process for the inter-frame prediction coding will beexplained. FIG. 6 shows an outline of the inter-frame prediction coding.Pictures are divided into three types, namely an intra-frame codedpicture (hereinafter referred to as an I picture), a one directionprediction coded picture (hereinafter referred to as a P picture), and aboth direction prediction coded picture (hereinafter referred to as a Bpicture).

For example, in the case where one picture out of N pictures is set asan I picture, one picture out of M pictures is set as a P picture or Ipicture, (N×n+M)th picture constitutes an I picture, (N×n+M×m)th picture(m≠1) constitutes a P picture, pictures from (N×n+M×m+1)th picture to(N×n+M×m+M−1)th picture constitute B pictures, where n and m areintegers and 1≦m≦N/M. At this time, pictures from (N×n+1)th picture to(N×n+N)th picture are referred to as a GOP (group of pictures) insummary.

FIG. 6 shows a case in which symbols N and M are defined as N=15 andM=3. In FIG. 6, the I picture is not subjected to the inter-frameprediction but only to the intra-frame conversion coding. The P pictureis subjected to a prediction from the I picture immediately before the Ppicture or from the P picture. For example, the 6^(th) picture in FIG. 6is a P picture. The 6^(th) picture is subjected to the prediction fromthe 3^(rd) I picture. Further, the 9^(th) P picture in FIG. 6 issubjected to the prediction from the 6^(th) P picture. The B picture issubjected to the prediction from I picture or the P picture immediatelybefore and after the B picture. For example, in FIG. 6, the 4^(th) and5^(th) B pictures are subjected to the prediction both from the 3^(rd) Ipicture and the 6^(th) P picture. Consequently, the 4^(th) and 5^(th)pictures are subjected to coding after coding of the 6^(th) picture.

Now operation of the data compressing circuit 202 will be explained inaccordance with FIG. 2. The memory circuit 301 outputs the digital videopicture signals which are inputted after rearranging the signals in thecoding order. In other words, as described above, for example, the firstB picture is coded after the 3^(rd) I picture in FIG. 6. Consequently,the order of pictures are rearranged. FIG. 7 shows an operation of thisarrangement. A picture sequence inputted as shown in FIG. 7A isoutputted in the order shown in FIG. 7B.

Further, the video signal 321 outputted from the memory circuit 301 issubjected to DCT in the direction of space axis after a differencebetween pictures from the prediction picture 323 outputted from themotion compensation predicting circuit 310 at the subtracter 302 toreduce the redundancy in the direction of the time axis. The convertedcoefficient is quantized and variable-length coded followed by beingoutputted via the transmission buffer 306. In the meantime, thequantized conversion coefficient is inversely quantized and is subjectedto an inverse DCT. After that, the coefficient is added to theprediction picture 323 at the adder 309 and a decoded picture 322 isobtained. The decoded picture 322 is inputted to the motion compensationpredicting circuit 310 for the subsequent coding of pictures.

Subsequently, an operation of the motion compensation predicting circuit310 will be explained in accordance with FIG. 3. The motion compensationpredicting circuit 310 uses two reference pictures which are stored inthe frame memory 404 a and the frame memory 404 b to perform a motioncompensation prediction of the video signal 321 outputted from thememory circuit 301 for outputting the prediction picture 323.

In the beginning, in the case where the picture 322 coded and decoded asdescribed above is either an I picture or a P picture, this picture 322is stored in the frame memory 404 a or the frame memory 404 b for codingthe subsequent picture. At this time, the switcher 403 is switched sothat the frame memory out of the two frame memories 404 a and 404 bwhich is renewed prior to the other in time is selected. However, whenthe decoded picture 322 is a B picture, writing is not performed at theframe memory 404 a and the frame memory 404 b.

For example, when 1^(st) and 2^(nd) pictures in FIG. 7 are coded by suchswitching of the switch 403, the Oth P picture and the 3^(rd) I pictureare stored in the frame memory 404 a and frame memory 404 b,respectively. Further, when the 6^(th) P picture is coded and decoded,the frame memory 404 a is rewritten into the decoded picture of the6^(th) P picture.

Consequently, when the 4th and the 5th B pictures are coded, the 6th Ppicture and the 3rd I picture are stored in the frame memories 404 a and404 b, respectively. Further, when the 9th P picture is coded anddecoded, the frame memory 404 b is rewritten into the decoded picture ofthe 9th P picture. As a consequence, when the 7th B picture and the 8thB picture are coded, the 6th P picture and the 9th P picture are storedin the frame memories 404 a and 404 b, respectively.

When the video signal 321 outputted from the memory circuit 301 isinputted to the motion compensation predicting circuit 310, the motionvector detecting circuits 405 a and 405 b detect a motion vector on thebasis of a reference picture stored in the frame memories 404 a and 404b and output a motion compensation prediction picture. In other words,the video signal 321 is divided into a plurality of blocks. Then a blockis selected so that the prediction distortion becomes the smallest inthe reference picture with respect to each block. Then the relativeposition of the block is outputted as the motion block, and at the sametime this block is outputted as the motion compensation predictionpicture.

In the meantime, the prediction mode selector 406 selects a picturewhere the prediction distortion is the smallest out of two motioncompensation prediction pictures outputted from the motion vectordetecting circuits 405 a and 405 b or an average picture thereof. Then,the selected picture is outputted as a predicted picture. At this time,when the video signal 321 is not a B picture, the motion compensationprediction picture is always selected and outputted which corresponds tothe reference picture which is inputted prior to the other before intime. Further, the prediction mode selector 406 selects either coding inpictures in which prediction is not performed or prediction coding bythe selected prediction picture in such a manner that the selectedcoding has a better coding efficiency.

At this time, when the video signal 321 is an I picture, the coding inpictures is always selected. When the coding in pictures is selected, asignal representative of the coding in the picture mode is outputted asa prediction mode. In the meantime, when the prediction coding betweenpictures is selected, a signal representative of a selected predictionpicture is outputted as a prediction mode. The switcher 407 outputs azero signal when the prediction mode outputted from the prediction modeselector 406 is a mode of coding in pictures. If the prediction mode isnot the mode of coding in pictures, the prediction mode selector 406outputs the prediction picture.

It follows from the aforementioned fact that when the video signal 321outputted from the memory circuit 301 is an I picture, the motioncompensation predicting circuit 310 always outputs the zero signal as aprediction picture 323, the I picture is not subjected to theinter-frame prediction but to the intra-frame conversion coding. In themeantime, when the video signal outputted from the memory circuit 301 isthe 6th P picture in FIG. 6, the motion compensation prediction circuit310 performs the motion compensation prediction from the 3rd I picturein FIG. 6 and outputs the prediction picture 323. Further, when thevideo signal 321 outputted from the memory circuit 301 is the 4th Bpicture shown in FIG. 6, the motion compensation prediction circuit 310performs the motion compensation prediction from the 3rd I picture andthe 6th P picture shown in FIG. 6 and outputs the prediction picture 323

Subsequently, an operation of the transmission buffer 306 will beexplained. The transmission buffer 306 converts video datavariable-length coded by the variable-length encoder 305 into abitstream of the MPEG video signal. Here, the stream of the MPEG has asix layer structure shown in FIG. 5. Header information which is anidentification code is added for a sequence layer 621, a GOP layer 622,a picture layer 623, a slice layer 624 and a block layer 626 toconstitute the layer structure.

Further, the transmission buffer 306 decomposes a bitstream of a videosignal and a bitstream of an audio signal into a plurality of packetsrespectively so that these packets are multiplexed including asynchronization signal thereby constituting a system stream of aMPEG2-PS (program stream). Here, the MPEG2-PS includes a pack layer anda packet layer as shown in FIG. 8. Then the header information is addedto the packet layer and the pack layer. In the conventional example, asystem stream is constituted so that data of one GOP portion of thevideo data is included.

Here, the pack layer has a structure in which the packet layer is boundat the upper layer of the packet layer. Each packet layer whichconstitutes the pack layer is referred to as a PES packet. In addition,header information of the pack layer shown in FIG. 8 includes anidentification signal of a pack and a synchronous signal whichconstitutes a basis of a video signal and an audio signal.

In the meantime, in the packet which constitutes the packet layer, threekinds of PES packets exist as shown in FIG. 9. Here, a second stagepacket shown in FIG. 9 is a video/audio/private 1 packet wherein a codefor identifying the front of the packet and time stamp information orthe like (PTS and DTS) needed at the time of decoding each packet asheader information are added before the packet data. However, the timestamp information PTS is a time control information of the reproductionoutput and is information for controlling a decoding order of datastream of each packet at the time of reproduction. Further, DTS is timecontrol information at the start of decoding and is information forcontrolling the transmission order of decoding data.

The third stage packet shown in FIG. 9 is a private 2 packet where userdata is written. Further, the lowest stage packet is a padding packetwhere all the packet data is masked with “1”. The header information inthe private 2 packet and padding packet is constituted of a start codeof a packet and a packet length.

As described above, the video data and audio data items are convertedinto a system stream of the MPEG2-PS by the transmission buffer 306 andis converted for each of the frame sectors. This information issubjected to error correction processing, and at the same time, theinformation is modulated to minimize the interference between codes onthe disc and is recorded on the optical disc 212. At this time, forexample, data amount for each of the GOP unit is set to an approximatelythe same amount. Then, it is apparent that the edition for each of theGOP unit can be made by distributing the data into sectors which areequal to integer times of the frame cycle.

Subsequently, an operation at the time of playback will be explained. Atthe time of the playback, the video information recorded on the opticaldisc 212 is amplified with the playback amplifier 213. After theinformation is restored to digital data at the demodulator 214 and theerror correction decoder 215 followed by being restored as pure originalvideo data free of data such as an address and a parity at the framesector inverse converting circuit 216. Then, the data is inputted intothe data extending circuit 217 which has a structure shown in FIG. 4.The system stream which includes a MPEG2-PS is inputted to thetransmission buffer 501.

At the transmission buffer 501, the system stream which is inputted isdecomposed into a pack unit. After that, each PES packet is decomposedin accordance with the header information thereby reconstructing thebitstream of the video data and audio data which is decomposed in thePES packet unit. Further, with respect to the video data, the stream isdecomposed to the block layer shown in FIG. 5 so that the block data andthe motion vector data is decomposed and outputted.

The block data outputted from the transmission buffer 501 is inputted inaccordance with the variable-length decoder 502 so that thevariable-length data becomes a fixed length data, inversely quantizedand is subjected to the inverse DCT to be outputted to the adder 506. Inthe meantime, the prediction data decoding circuit 505 decodes theprediction picture in accordance with the motion vector outputted fromthe transmission buffer 501 to be outputted to the adder 506.

In this case, the prediction data decoding circuit 505, like the motioncompensation predicting circuit 310, provides a frame memory for storingthe I picture and P picture data which is decoded by the adder 506.Incidentally, with respect to a method for renewing the referencepicture data an explanation will be omitted because the method is thesame as the case of coding the data.

The adder 506 adds the output of the prediction data decoding circuit505 and the output of the inverse DCT circuit 504 to be outputted to thememory circuit 507. Here, at the time of coding the data, the frame isrearranged in accordance with the order of coding the data as shown inFIG. 7 with respect to the video signals which are continuous in time.Therefore, in the memory circuit 507, the data inputted in the ordershown in FIG. 7B is rearranged so that the picture data continues intime and is outputted to the D/A converter 218.

Subsequently, the picture retrieval and the high speed playback thereofwill be shown in the case where data with such a coding structure isrecorded on the optical disc. In the case where the coding structureshown in FIG. 6 is provided, the high speed playback of the picture canbe performed when the data is played back in the unit of the I picture.In this case, the track jump is performed immediately after the Ipicture is played back. Then, the following or the preceding GOP isaccessed so that the I picture is played back there. In the case shownin FIG. 6, the high speed feeding playback and rewinding playback can beactualized by repeating such an operation.

However, since this GOP rate is a variable bit rate, it is impossible torecognize at all where the front of the following GOP is located.Consequently, the optical head is allowed to appropriately jump tolocate the front of the GOP. Thus, it is impossible to determine whichtrack should be accessed.

In addition, the I picture has a large amount of data. Thus, when onlythe I picture is played back in a continuous manner, like a specialplayback, the picture cannot be played back at a frequency of 30 Hz likea normal animated picture because of a limit on the reading speed fromthe disc. Even when the optical head jumps after the completion of the Ipicture playback, the intermission for the renewal to the following Ipicture becomes longer so that the operation lacks in smoothness.

The conventional digital video signal record and playback device, isconstituted in the aforementioned manner. In the case where a high speedplayback is performed at several times speed by using the I picture andthe P picture, the I picture data and the P picture data is read afterthe front of the GOP is detected from bitstreams which are recorded on arecording medium or the like such as an optical disc or the like.Consequently, in the case where the data amount of the I picture and theP picture become very large, or in the case where it takes much time tosearch the front of the GOP, time for reading the data from therecording medium becomes insufficient. Thus there arises a problem inthat the data all the I picture and the P picture cannot be read so thatthe high speed playback cannot be realized.

In the conventional digital video signal record and playback device, ittakes much time to input I picture data which has a large amount of dataeven when the high speed playback is performed only by using the Ipicture. Consequently the special playback which surpasses tens of timescannot be realized. In this case, a higher speed special playback can berealized by playing back one I picture for several GOP. There is aproblem in that the interval for the renewal of played back picture willbe prolonged so that the content of the picture will become vague.

Since the conventional video signal record and playback device is codedas described above, only the I picture having a large amount of data isdecoded at The time of the skip search (watching data through a rapidplayback). Consequently, the optical head is allowed to jump withoutplaying back data sufficient for the decoding. Otherwise, when asufficient amount of data is played back, the time for the playback ofdata is long, the destination to which the GOP is to jump must be set toa considerably far place causing a problem that the number of scenesoutputted to the screen becomes few.

In addition, since the sector address of the following GOP cannot berecognized because of the variable rate, it is not verified whether ornot the front of the GOP is located at the track to which the jump ismade. Consequently, there arises a problem in that a plurality of discrotation are required to locate the front of the GOP at the track ofdestination and the number of scenes which are outputted to the screenbecomes much fewer at the time of the special playback. Further, therearises a problem in that if the sector address can be recognized, nomeans is available for judging to what extent data can be played backfor the optical head jump with the result that no judgement can be madewithout passing through the video decoder, and the efficiency at whichthe optical head jumps is lowered.

As other conventional digital video signal record and playback devices,some devices are disclosed in, for example. Japanese Patent ApplicationLaid-Open No. HEI 6-98314 (1994), Japanese Patent Application Laid-OpenNo. HEI 6-78289 (1994) and the like. One example is shown in FIG. 10. InFIG. 10, reference numeral 775 denotes a video signal generator such asa camera, a VTR or the like, 776 an audio signal generator such as amicrophone, a VTR or the like, 762 a video signal encoder, 763 an audiosignal encoder, 777 a system layer bitstream generator, 778 an errorcorrection coder, 779 a digital modulator, 780 an optical disc, 756 aplayback amplifier, 786 a detector, 781 a digital demodulator, 758 anerror corrector, 759 a system stream processor, 782 a video signaldecoder, 783 an audio signal decoder, 784 a monitor and 785 a speaker.

Currently, optical discs generally used have a diameter of 120 mm. Theseoptical discs are normally capable of recording 600 M byte or more data.Quite recently, these optical discs are capable of recording videosignal and an audio signal for 74 minutes at a data rate of about 1.2Mbps. At the time of data recording, a video signal is inputted to thevideo signal encoder 762 from the video signal generator 775 forencoding the video signal. From the audio signal generator 776, theaudio signal is inputted to the audio signal encoder 763 for encodingthe audio signal. The process for multiplexing the header or the like tothese two encoded signals is carried out by the system layer bitstreamgenerator 777. After the error correction code is appended by the errorcorrection coder 778, the error correction signal is digitally modulatedwith a digital modulator 779 thereby generating a bitstream forrecording. This bitstream creates a mother disc with a recording means(not shown), and the content of the mother disc is copied to the opticaldisc 780 with the result that a commercially available video softwaredisc is prepared.

In a playback device for users, a signal obtained from the videosoftware disc by the optical disc is amplified with the playbackamplifier 756 to input a playback signal to the detector 786. After thisplayback signal is detected with the detector 786, the digitaldemodulator 781 digitally demodulates the signal to correct errors withan error corrector 758. After this, the video signal area is extractedfrom the signal which has been error corrected, and this extracted datais decoded at the video signal decoder 782 and outputted together withthe audio signal decoded by the audio signal decoder 783 to the monitor784 and the speaker 785 respectively.

A typical method for coding this video signal is an MPEG 1 and an MPEG 2referred to as an MPEG (Moving Picture Experts Group) method which is aninternational standard coding method. A concrete example of codingmethod will be explained with respect to an example of MPEG 2.

FIG. 11 shows a block diagram of an video signal coding part in aconventional digital signal record and playback device for explainingthe MPEG2 coding method. FIG. 12 is a block diagram of an video signaldecoding unit in a conventional digital signal record and playbackdevice for explaining a decoding method. Further, FIG. 13 is a viewshowing a concept of the mobile picture processing for the video signalcoding in the conventional digital signal record and playback device forexplaining the grouping of mobile pictures according to the codingmethod of the MPEG 2. Referring to FIG. 13, IBBPBBP designates—, I an Ipicture, B a B picture and P a P picture. For example, in FIG. 13A,mobile pictures from I to the one immediately before the appearance ofanother I are grouped in a definite number of frames. The number offrames of the pictures which constitute this group is normally 15 framesin many cases. However, the number is not limited to any specificnumber.

The GOP, a group of pictures which constitutes this group includes atleast one frame of I picture which can be decoded completely in oneframe. The GOP also includes a P picture coded through the motioncompensation prediction by one direction prediction of the time systemon the basis of the I picture and a B picture coded by both directionprediction of the time system on the basis of the I picture and the Ppicture. Incidentally, the arrows in FIGS. 13A and 13B representprediction relations.

In other words, the B picture can be coded and decoded only after the Ipicture and the P picture are prepared. The initial P picture in the GOPcan be coded and decoded after the I picture before the P picture isprepared. The second P picture and P picture after that can be coded anddecoded when the P picture immediately before the P picture is prepared.Consequently, in the absence of the I picture, either the P or Bpictures cannot be coded and decoded.

Referring to FIG. 11, reference numeral 787 denotes a picturerearranger, 788 a scan converter, 789 an encoder buffer, 790 a modedeterminer, 702 a motion vector detector, 706 a subtracter, and 708 aDCT circuit which has a field memory, a frame memory, and DCTcalculator. Reference numeral 710 denotes a quantizer, 714 an inversequantizer, 716 an inverse DCT circuit, 718 an adder, 720 an imagememory, 722 a rate controller and 726 a variable-length encoder.

Referring to FIG. 12, reference numeral 733 denotes a variable-lengthdecoder, 736 an inverse DCT circuit, 737 an image memory, 788 an adder,739 an inverse scan converter. Incidentally, the motion vector detector702 and the mode determiner 790 combines together to represent a motionvector detecting unit.

Subsequently, on the basis of FIGS. 11 though 13, an operation of adigital video signal record and playback device will be explained.Referring to FIG. 11, the picture rearranger 787 rearranges pictures forcoding in an order shown in FIG. 13. Then the scan converter 788converts the scan from the raster scan to the block scan. This picturerearrangement and the conversion processing from the raster scan to theblock scan are generally referred to as preprocessing. The picturerearranger 787 and the scan converter 788 are generally referred to aspreprocessor. The inputted picture data is subjected to block scan inthe order of encoding. When the picture is an I picture, the picturepasses through the subtracter 706. When the picture is a P picture or aB picture, the picture is subtracted with the reference picture and thesubtracter 706.

At this time, the motion vector detector 702 determines the motiondirection and the motion quantity (the input of the original picture tothis motion vector detector 702 may be a picture after the picturerearrangement or a picture after the block scan as an original picture,but the circuit size is smaller in the latter case. Further, thereference picture must be inputted from the image memory 720 but thereference arrow in the drawing is omitted) with the result that a signalin the area in consideration of the portion of the direction andquantity from the image memory 720 may be read. At this time, the modedeterminer 790 determines whether both direction prediction is used or aone direction prediction may be used.

The substraction with the reference screen in consideration of themotion vector is performed at the subtracter 706. Even pictures with asmall electric power are constituted so that the coding efficiency isheightened. The output from the subtracter 706 is collected either in aunit of field or in a unit of frame at the DCT circuit 708 to besubjected to a DCT process and converted into data in a frequencycomponent. This data is inputted to the quantizer 710 where the weightis different for each of the frequency. The data is scanned in a zigzagmanner in two dimensions over low frequency components and highfrequency components to be subjected to a run length coding and aHuffman coding.

This data which has been subjected to the run length coding and Huffmancoding is controlled for variable-length coding so that a quantizingtable is scaled by using the rate controller 722 to allow the data toagree with a target code quantity. The data that has been subjected tovariable-length coding is normally outputted via the encoder buffer 789.The quantized data is brought back to the inverse quantizer 714 to bebrought back to an original picture space data by the inverse DCTcircuit 716 with the result that data which is the same as the decodeddata is obtained by the adder 718 by adding the original picture spacedata to the data referenced by the subtracter 706.

FIG. 12 shows a schematic block structure of a decoder. Thevariable-length decoder 733 decodes picture data including headerinformation such as the motion vector, the coding mode, the picture modeor the like. After this decoded data is quantized, the inverse DCTcircuit 736 performs the inverse DCT calculation (incidentally, in FIG.12, the inverse quantizer located in the front stage of the inverse DCTcircuit 736 is omitted). By referring to the picture data from the imagememory 737 in consideration of the motion vector, the motioncompensation prediction is decoded by adding the picture data that hasbeen referred to with the data after the inverse DCT by the adder 738.This data is converted into a raster scan with the inverse scanconverter 739 to obtain and output an interlace picture.

Further, in accordance with the variable transmission rate disc systemintroduced in “the variable transmission rate disc system and the codequantity control method” in a publication of Mr. Sugiyama et al, at the1994 annual meeting of the Television Society, a proposal is made on ahigher quality digital video signal encoding method. This is a method inwhich an encoding rate is fixed with one program (for example, a firstset) so that each GOP is set at a rate depending on the difficulty ofthe design and encoded. FIG. 14 is a block diagram showing a videosignal coding unit in a conventional digital signal record and playbackdevice. In FIG. 14, reference numeral 791 denotes a motion compensationpredictor, 792 a code amount memory, 793 a GOP rate setting unit, 794 acode amount assigning unit, 795 a subtracter, and 796 a code amountcounter and 797 a switch. The GOP rate setting unit 793 shown in FIG. 14is set to change the setting of the quantizing value according to thedifficulty of the design pattern. In other words, while the switch 797is connected to the virtual coding side, the output of thevariable-length encoder 726 is inputted to the code amount counter 796so that the code amount counter 796 counts the code amount to be storedin the code amount memory 792.

The GOP rate setting unit 793 determines the virtual code amount in thewhole one program on the basis of the code amount stored in this codeamount memory 792 to set and calculate the optimal encoding rate in eachGOP. The code assignment at this time is calculated from the code amountassigning unit 794 for the preparation of the actual encoding. When theswitch 797 is connected to the actual coding side, the code amountassignment amount and the value of the code amount counter 796 arecompared so that the switch 797 is operated to control the quantizer 710on the basis of the actual code amount. In this manner, a small codeamount is assigned to an easy design and a large code is assigned to adifficult amount so that the coding difficulty that gradually changes inthe program is absorbed. As a consequence, it has been reported that thepicture quality of what is recorded at a rate of 3 Mbps by using thismethod is approximately the same as the picture quality of what is codedat a rate of 6 Mbps.

In consideration of the possibility of the skip search in the digitalvideo signal record and playback device using an optical disc, when theI picture and the P picture are played back for fast rewinding even whenthe front of the GOP can be accessed at a high speed, the P picture islocated at an appropriate position in the GOP so that there arises aneed of operating the optical head while searching data on thebitstream. However, such a control cannot be made in time because of thetime constant of a servo such as an actuator or the like. One GOPnormally includes 15 frames of pictures, and in NTSC scanning method,0.5 second is available for finding the front of the GOP. However, inorder to detect the front of a certain GOP, the bitstream requires thereading of 1/2 or more for reading 1/3 picture at a frame rate even whenan attempt is made to read the I picture or the P picture at the time ofthe skip search with the result that the reading speed has to be set to2.5 times faster or even faster than the normal speed when the headmovement time is set to 200 milliseconds. This exceeds the responselimit of the actuator. In a normal playback method, the skip search issubstantially impossible to carry out.

In accordance with the conventional digital video signal record andplayback device, the signal is coded in this manner. Thus, when anattempt is made to perform the skip search like a video tape recorder, aperfect playback picture cannot be obtained in the case where the datais played back which does not allow obtaining a complete originalpicture from one picture data item like the B picture. Particularly, inthe skip search, jerkiness (unnatural movement) is generated withrespect to the output processing in the unit of frame. When a variablerate recording is performed with a good playback picture quality, therearises a problem in that the difficulty of accessing the front of theGOP itself increases since the position of the front address of the GOPchanges, with the result that a space is formed in a disc area due todisuniform unit of the GOP.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a digital video signalrecord and playback device which is capable of performing a specialplayback by using an I picture with a large data amount and obtaining aplayback picture with a good quality, and a method for recording andplaying back the same.

Another object of the present invention is to provide a digital videosignal record and playback device which is capable of performing a highspeed playback by using an I picture and a P picture with a large dataamount and obtaining a playback picture with a good quality, and amethod for recording and playing back the same.

Still another object of the invention is to provide a digital videosignal record and playback device which is capable of realizing animprovement in the access characteristics of the GOP under thepresupposition of adopting the coding of a variable bit rate whileobtaining a favorable skip search, and a method for recording andplaying back the same.

Further another object of the invention is to provide a digital videosignal record and playback device which is capable of realizing animprovement in the access characteristics of the GOP and an effectiveuse of space area on a storing medium under the presupposition ofadopting the variable rate coding while performing a skip search, and amethod for recording and playing back the same.

With the digital video signal record and playback device of the presentinvention, when the video signal is recorded in the unit of GOP, oneframe is divided into n areas with respect to the I picture so that eacharea is coded and recorded at the front of one GOP in order from thearea located at the central part of the screen. At the same time, theaddress information of each area of the I picture is simultaneouslyrecorded as header information. At the time of the special playback,only the data of the I picture in the area located at the central partof the screen is read, and a special playback picture is outputted bymasking a definite value of data with respect to the area where the datais not read. Consequently, compared with the case where all the Ipictures having a great amount of data are played back, a specialplayback can be realized at a faster speed.

In the aforementioned video signal record and playback device, specialplayback pictures are outputted by extending the central area that isread over the whole screen. Consequently, since the data at the centerportion of the screen is extended to synthesize the playback picture,the area in which data cannot be read becomes inconspicuous and theplayed back picture becomes favorable to watch.

With the digital video signal record and playback device of the presentinvention, the video signal is recorded in the unit of GOP, and oneframe is divided into n areas with respect to the I picture so that eacharea is coded and recorded at the front of one GOP in order from thecentral part of the screen. When the video signal is read and playedback from a recording medium such as an optical disc where the addressinformation of each area in the I picture is simultaneously recorded asheader information, at the time of the special playback only the data ofthe I picture in the area located at the central part of the screen isread. With respect to an area where the data is not read, the specialplayback picture is outputted by masking the data to a definite value.Consequently, compared with the case where all the I pictures are playedback, the special playback can be realized at a faster speed.

In the aforementioned digital video signal record and playback device,special playback pictures are outputted by extending the read centralpart of the area over the whole screen. Consequently, the area in whichdata cannot be read becomes inconspicuous and the playback picturebecomes favorable to watch.

With another digital video signal playback device of the presentinvention, when the video signal is recorded in the unit of GOP, oneframe is divided into n areas so that each area is coded and is recordedin order from an area located at the central part of the screen at thefront of the one GOP. At the same time, the address information of eacharea of the I picture is simultaneously recorded as header information.At the time of the special playback, only the data of the I picture isread in the unit of area and is outputted as a playback picture. In thecase where all the areas in the I picture cannot be read during adefinite time, the special playback picture is outputted byinterpolating the picture with the data of the preceding screen.Consequently, the area located at the central part of the screen isgiven a priority to be played back with the result that the interpolatedplayback picture becomes favorable to watch.

With still another digital video signal record and playback device ofthe present invention, when the video data is recorded in the unit ofGOP, one frame is divided into n areas with respect to the I picture sothat each area is coded and recorded in order from the central part ofthe screen at the front of the one GOP. At the same time, the addressinformation of each area of the I picture is simultaneously recorded asheader information. At the time of the special playback, only the dataof the I picture is read in the unit of area, and regions in the areas1, 2, - - - n are read one by one from consecutive n I pictures with theresult that pictures for one screen portion is synthesized and isoutputted as a playback picture. When all the areas of the I picturecannot be read in a definite time, the special playback picture isoutputted by interpolating the picture with the preceding screen data.Consequently, the area located in the central part of the screen isgiven a priority to be reproduced. Since one screen is synthesized withn I pictures, the interpolated playback picture becomes inconspicuous.

With still another digital video signal record and playback device ofthe present invention, when the video picture is recorded in the unit ofGOP, one frame is divided into n areas with respect to the I picture sothat each area is coded. When the I picture is recorded at the front ofone GOP in summary for each area, the position of the area which isinitially recorded in the unit of GOP is scrolled for recording. At thesame time, the address information of each area in the I picture issimultaneously recorded as header information. At the time of thespecial playback, only the data of the I picture is read in the unit ofarea and is outputted as a playback picture. In the case where all the Ipictures can not be read in a definite time, the special playbackpicture is outputted by interpolating the picture with data of thepreceding screen. Consequently, the position of the area is scrolled inthe unit of GOP, one screen can be played back in an even manner.

With still another digital video signal record and playback device ofthe present invention, when the video data is recorded in the unit ofGOP unit, one frame is divided into n areas with respect to the Ipicture so that each area is coded, is divided into an error correctionblock unit, and is recorded in order from the area located in thecentral part of the screen at the front of the one GOP. At the sametime, the address information of each area of the I picture issimultaneously recorded as header information. At the time of thespecial playback, only the data of the I picture is read in the unit oferror correction block and is outputted as a playback picture. In thecase where all the I picture cannot be read in a definite time, thespecial playback picture is outputted by interpolating the picture withthe data of the preceding screen. Consequently, since the area locatedat the central part of the screen is given a priority to the playback,the playback picture becomes favorable to watch.

With still another digital video signal record and playback device ofthe present invention, when the picture data is recorded in the unit ofGOP, one frame is divided into n areas with respect to the I picture andthe P picture so that each area is coded and the area located in thecentral part of the screen is recorded in order from the area located inthe center at the front of the one GOP. At the same time, the addressinformation of each area of the I picture and the P picture issimultaneously recorded as header information. At the time of thespecial playback, the data of the I picture and the P picture are readin the unit of area and is outputted as a playback picture. In the casewhere all the areas of the I picture or the P picture cannot be readwithin a definite time, the special playback picture is outputted byinterpolating the picture with the data of the preceding screen.Consequently, since the area located at the central part of the screenis give a priority in playback, interpolated playback picture becomesfavorable to watch.

With still another digital video signal record and playback device ofthe present invention, when the video signal is recorded in the unit ofGOP, one frame is divided into n areas with respect to the I picture andthe P picture so that each area is encoded and is recorded in order froman area located at the central part of the screen at the front of oneGOP. At the same time, the address information of each area of the Ipicture is simultaneously recorded as header information. At the time ofthe special playback, only the data of the I picture and the P pictureare read in the unit of area, and regions of areas 1, 2, - - - , n areread from continuous n I pictures and P pictures to synthesize a pictureof one screen portion and is outputted as a playback picture. In thecase where all the areas of the I picture or the P picture cannot beread within a definite time, the special playback picture is outputtedby interpolating the picture with the data of the preceding screen.Consequently, since the area located at the central part of the screenis given a priority in playback, interpolated playback picture becomesinconspicuous.

With still another digital video signal record and playback device ofthe present invention, when the video signal is recorded in the unit ofGOP, one frame is divided into n areas with respect to the I picture andthe P picture so that each area is encoded in the unit of frame. Whenthe divided frame is fixed for each area at the front of one GOP and isrecorded, the position of the area which is initially recorded in theunit of frame is scrolled. At the same time, the address information ofeach area in the I picture is simultaneously recorded as headerinformation. At the time of the special playback, only the data of the Ipicture is read in the unit of area and is outputted as a playbackpicture. In the case where all the I pictures can not be read in adefinite time, the special playback picture is outputted byinterpolating the picture with data of the preceding screen.Consequently, the order in which the area of the I picture and the Ppicture is recorded is scrolled in the unit of GOP, a playback picturefor one screen portion can be played back in an even manner.

With still another digital video signal record and playback device ofthe present invention, when the video signal is recorded in the unit ofGOP unit, one frame is divided into n areas with respect to the Ipicture and the P picture so that each area is encoded and is divided inthe error correction block unit. Then the divided frame is recorded inorder from an area located at the central part of the screen at thefront of the one GOP. At the same time, the address information of eacharea of the I picture is simultaneously recorded as header information.At the time of the special playback, only the data of the I picture isread in the unit of error correction and is outputted as a playbackpicture. In the case where all the I pictures cannot be read within adefinite time, the special playback picture is outputted byinterpolating the picture with the data of the preceding screen.Consequently, since the area located at the central part of the screenis given a priority in playback, interpolated playback picture becomesfavorable to watch.

In accordance with the digital video signal playback method (device), atleast the I picture which is subjected to the intra-frame coding isdivided depending on the frequency area, quantizing level or spaceresolution so that a bitstream of video data is constituted wherein thedata more important as a picture out of data divided as least withrespect to the I picture is arranged at the front. Then the addressinformation of the divided data is arranged as header information at thefront of the bitstream of the video data to constitute a packet. Thedata recorded on the recording medium is rearranged at the time of thenormal playback in the data order before dividing the data in accordancewith the header information in the packet to be outputted. At the timeof the special playback, data arranged at the front is decoded andoutputted for the special playback. Consequently, the data decreaseswhich is to be accessed at the time of the special playback by dividingdata depending on the frequency area, quantizing level or the spaceresolution with the result that a smooth special playback picture can beobtained. Further, since the address of the divided data is recorded asheader information of the system stream, the number of bytes that shouldbe instantly played back at the time of the playback can be known withthe result that the optical head can effectively jump at the time of thespecial playback. Further, at the time of the normal playback, the datais rearranged on the basis of the address with the result thatdisadvantage resulting from the division of data can be prevented whenplayed back.

In accordance with the digital video signal record and playback method(device), at least the I picture which is subjected to the intra-framecoding is divided depending on the frequency area, the quantizing leveland the space resolution, so that a bitstream of video data isconstituted wherein the data more important as a picture out of datadivided as least with respect to the I picture is arranged at the front.Then the address information of the divided data is arranged as headerinformation at the front of the bitstream of the video data toconstitute a packet. The data recorded on the recording medium isrearranged at the time of the normal playback in the data order beforedividing the data in accordance with the header information in thepacket to be outputted. At the time of the special playback, dataarranged at the front is decoded and outputted for the special playback.Consequently, the data decreases which is to be accessed at the time ofthe special playback by dividing data depending on the frequency area,quantizing level or the space resolution with the result that a smoothspecial playback picture can be obtained. Further, since the address ofthe divided data is recorded as header information of the system stream,the number of bytes that should be instantly played back at the time ofthe playback can be known with the result that the optical head caneffectively jump at the time of the special playback. Further, at thetime of the normal playback, the data is rearranged on the basis of theaddress with the result that disadvantage resulting from the division ofdata can be prevented when recorded and played back.

In accordance with another digital video signal record and playbackmethod (device), at least the I picture which is subjected to theintra-frame coding at the time of recording is divided into n areas(n>1) so that the I picture divided into n areas is rearranged in theunit of area so that a bitstream of video data is constituted whereinthe area located at the center on the screen is arranged at the front.Then, the address information of the I picture divided into n areas isarranged at the front of the bitstream of data to constitute a packetand is recorded on the recording medium. At the time of the normalplayback, the data of the I picture is rearranged in the unit of areaand is outputted in accordance with the header information arranged atthe front of the packet. At the time of the special playback, thespecial playback can be performed by outputting only the data of the Ipicture that can be read in a definite time from the front of thepacket. Consequently, the data that should be accessed at the time ofthe special playback decreases by dividing data in the area of thescreen at the time of recording. Since the address of the divided datais recorded as header information of the system stream, the number ofbytes that should be instantly played back at the time of the playbackcan be known with the result that the optical head can effectively jumpat the time of the special playback the address jump can be performed ina certain time unit. Further, at the time of the normal playback, thedata is rearranged on the basis of the address with the result thatdisadvantage resulting from the division of data can be prevented whenrecorded and played back.

In accordance with another digital video signal record and playbackmethod (device), at least the I picture data which is subjected to theintra-frame coding is divided into n areas (n>1) so that the I picturedivided into n areas is rearranged in the unit of area so that abitstream of video data is constituted wherein the area located at thecenter on the screen is arranged at the front. Then, the addressinformation of the I picture divided into n areas is arranged at thefront of the bitstream of video data as header information to constitutea packet. At the time of the normal playback, the I picture datarearranged for each area in accordance with header information arrangedat the front of the packet is rearranged in the area unit and isoutputted from the recording medium on which the data is recorded. Atthe time of the special playback, the special playback is performed byoutputting only the data which can be read in a definite time.Consequently, the address jump can be performed in a certain time unitat the time of the special playback by dividing the data in the area onthe screen with result that the data to be addressed at the time of thespecial playback decreases. Further, since the address of the divideddata is recorded as header information to the system stream, the numberof bytes that should be played back can be instantly detected at thetime of the playback with the result that the jump of the optical headat the time of the special playback can be efficiently performed.Further, since the data is rearranged on the basis of the address at thetime of the normal playback, the data can be played back without causingthe disadvantage resulting from the data division.

In accordance with still another digital video signal record andplayback method (device), at least the I picture which is subjected tothe intra-frame coding at the time of recording are divided with the lowfrequency area, the high frequency area, the quantizing level and thespace resolution with the result that the basic data out of the dividedI picture are rearranged in the unit of each area on the screen toconstitute a bitstream of the video data where the area located at thecentral part of the screen in the I picture is arranged at the front.The divided areas, the data division, and the address information of thepicture is arranged at the front of the bitstream of the video data asheader information to constitute a packet and is recorded on a recordingmedium. At the time of the normal playback, the data is rearranged inthe unit of area in accordance with the header information which isarranged at the front part of the packet and the data is outputted. Thedivided data is rearranged in the order of the original data. At thetime of the special playback, only the data of the I picture which canbe read in a definite time from the front of the packet is outputted forperforming a special playback. Consequently, at the time of therecording, the data is divided depending on the frequency, thequantization and the space resolution, and is divided in the unit ofarea on the screen. As a consequence, at the time of the specialplayback, the data to be accessed decreases so that a smooth specialplayback can be obtained by gradually decreasing the data amount to beaccessed at the time of the special playback. Further, since the addressof the divided data is recorded as header information and the number ofbytes that should be played back can be instantly detected at the timeof the playback, the jump of the optical head at the time of the specialplayback can be efficiently performed. Further, regarding the datadivided by a plurality of dividing means, the amount of data to be readcan be adjusted in accordance with the special playback speed to copewith a wide scope of the special playback speed. Further, since the datais rearranged on the basis of the address at the time of the normalplayback, the data can be played back without causing the disadvantageresulting from the data division.

In accordance with still another digital video signal playback method(device), at least the I picture which is subjected to the intra-framecoding are divided in accordance with the low frequency area, the highfrequency area, the quantizing level or the space resolution with theresult that the basic data out of the divided I picture is rearranged ineach area on the screen to constitute a bitstream of the video datawhere the area located at the central part of the screen in the Ipicture is arranged at the front. The divided areas, the data division,and the address information of the picture is arranged at the front ofthe bitstream of the video data as header information to constitute apacket and is recorded on a recording medium, from which the data isoutputted at the time of the normal playback by rearranging the data inthe unit of area in accordance with the header information arranged atthe front part of the packet. The divided data is rearranged in theorder of the original data. At the time of the special playback, onlythe data of the I picture which can be read in a definite time from thefront of the packet is outputted for performing a special playback.Consequently, the data is divided depending on frequency, quantizationand space resolution, and is divided in the unit of area on the screen.As a consequence, the data to be accessed at the time of specialplayback is decreased by dividing the data in the unit of area on thescreen. Further, since the address of divided data is recorded as headerinformation and the number of bytes that should be played back isinstantly detected at the time of the playback, the jump of the opticalhead at the time of the special playback can be efficiently performed.Further, regarding the data divided by a plurality of dividing means,the amount of the data to be read can be adjusted in accordance with thespecial playback speed to cope with a wide scope of the special playbackspeed. Further, since the data is rearranged on the basis of the addressat the time of the normal playback, the data can be played back withoutcausing the disadvantage resulting from the data division.

In accordance with still another digital video signal record andplayback method (device) (or a digital video signal playback method(device)), only the area that is located at the central part of thescreen of the I picture is read. With respect to the data in the areawhich is not read, the playback picture is synthesized by masking thedata to a definite value. Consequently, compared with the case where allthe I picture which has a large amount of data is played back, thespecial playback can be realized at a higher speed.

In accordance with still another digital video signal record andplayback method (device) (or a digital video signal playback method(device), only the area that is located at the central part of thescreen of the I picture is read. The playback picture is synthesized byextending the read-out area over the whole screen. Consequently,compared with the case where the whole I picture having a large dataamount is played back, the special playback can be realized at a higherspeed with the result that the area where the data cannot be readbecomes inconspicuous.

The digital video signal record device of the present invention includesfirst coding means for coding a video signal comprising a coded pictureincluding at least a picture subjected to the intra-frame coding out ofthe digital video signal coded by using the motion compensationprediction and the orthogonal transform, second coding means for codinga residual component through coding using the first coding means outputof the video signal, data arrangement means for arranging each of theoutput data outputted from the first and the second coding means at apredetermined position in each picture group data for each of thepicture group data. Compared with the case in which the first codingmeans codes all the video signals, the area to be accessed at least isdecreased by coding a basic part of the mobile picture. The secondcoding means codes video information which is not coded with the firstcoding means so that all the video information is coded with two codingmeans. Further, the data arrangement means rearranges data obtained bytwo coding means so that the data is favorable for the access of thehead. Consequently, coding can be made possible so that the amount ofcode that should be accessed at least at the time of the specialplayback is decreased. Thus, the arrangement of data that should beaccessed at least at the time of the special playback can be efficientlyperformed.

In the aforementioned digital video signal record device, the videoinformation is coded which is thinned at a predetermined interval withrespect to the video picture comprising coded picture including at leasta picture coded in the frame. Consequently, the first coding means codesthe thinned video picture so that the area to be accessed at least isdecreased. When only the data of the first coding means is accessed, thevideo picture can be coded so that the scene can be sufficientlyunderstood when the picture is decoded.

In the aforementioned digital video signal record device, the firstcoding means codes only the low frequency area which is orthogonallyconverted. The first coding means codes the picture data which ispartial in terms of frequency so that the area which is to be accessedat least is decreased. When only the data of the first coding means isaccessed, the video picture can be coded so that the scene can besufficiently understood when the picture is decoded.

In the aforementioned digital video signal record device, the firstcoding means roughly quantizes on a quantization level to be coded. Thefirst coding means codes the data of the upper bit which exerts a deepinfluence on the picture through the rough quantization so that the areato be accessed at least is decreased to be coded without decreasing theresolution. When only the data of the first coding means is accessed,the video picture can be coded so that the scene can be sufficientlyunderstood when the picture is decoded.

Another digital video signal record device of the present inventionextracts data in the low frequency component from a data array in whichthe video signal is segmented by predetermined bits, the video signalcomprising a coded picture including at least a picture subjected to theintra-frame coding out of the video signal which is coded using themotion compensation prediction and the orthogonal transform. The lowfrequency area of the video signal is segmented by segmenting the databy predetermined bits for each block. Consequently, it is easy to limitthe code amount to be within a fixed length. Besides, when the data inthe low frequency area is decoded, the data can be coded so that thecontent of the picture can be roughly understood.

The digital video signal playback device of the present inventionrearranges data in the low frequency area and data in the high frequencyarea into a predetermined order so that either of the mode for decodingthe rearranged data or the mode for selectively decoding the data in thelow frequency area. At the time of the normal playback, a completedecoded picture can be obtained by connecting two segmented coded data.At the time of the special playback, only the data in the low frequencyarea is decoded. Consequently, data can be decoded depending on theoperation state of the device with the result that a picture can beobtained to an extent that the rough content of the picture can begrasped.

In the aforementioned digital video signal playback device, when thedata is decoded in a mode of decoding only the data in the low frequencyarea, only the data that can be decoded is decoded. The data whichcannot be decoded in the vicinity of the boundary of a predeterminednumber of bits is discarded so that the data in the high frequency areais replaced with the fixed value for an inverse orthogonal transform.When the low frequency area out of two segmented coded data is decodedat the time of the special playback, only the data that can be decodedis decoded and the bit that cannot be decoded is discarded. The decodingof the abnormal data can be avoided. With respect to the remaining highfrequency area, the data is replaced with the fixed value and decodedwith the result that a decoded picture can be obtained free from datadistortion.

Still another digital video signal record device adds an end of theblock code to a coded data in each block of the video signal comprisinga coded picture including at least a picture subjected to theintra-frame coding out of the coded digital signals by using the motioncompensation prediction and the orthogonal transform when apredetermined number of bits as data in the low frequency area isattained. The aforementioned coded data which exceeds a predeterminednumber of bits is coded as a high frequency region data. Both the lowfrequency area and high frequency area of the block are coded in such amanner that the block is ostensibly terminated in the end of block (EOB)code. Consequently, when only data in the low frequency area is decoded,coded data can be obtained that can be decoded without requiring aredundant circuit such as discarding of the data.

Still another digital video signal record device of the presentinvention reconstructs data on the basis of the data in the lowfrequency area, the data in the high frequency area and the EOB code.Then, either a mode of decoding the reconstructed data or the mode ofselectively decoding only data in the low frequency area is selected sothat the coded data reconstructed on the basis of the result ofselection is decoded. With respect to the high frequency area, the datais replaced with a fixed value to perform an inverse orthogonaltransform. At the time of the normal playback, a complete decodedpicture is obtained from the coded data segmented by the EOBrespectively can be obtained. At the time of the special playback, onlydata in the low frequency area is decoded out of the coded data so thatboth the normal and special playback modes can be operated depending onthe operation state of the device with the result that a rough picturecan be obtained which allows us to understand the scene. Further, whenthe low frequency area is decoded out of the coded data, the remaininghigh frequency area of the block is replaced with the fixed value and isdecoded with the result that the area can be decoded free from datadistortion. Both the high frequency area and the low frequency area ofthe block can be decoded as if the block is ostensibly ended at the EOB.

Still another digital video signal record device of the presentinvention includes a low resolution coding means for coding data of thelow resolution component in which pixels are thinned with respect to avideo signal comprising a coded picture including at least a picture inthe frame out of the coded digital picture by using the motioncompensation prediction and the orthogonal transform, differentialcomponent coding means for coding a differential component with thepicture before thinning the pixels by interpolating the output data ofthe low resolution coding means, and information adding means forconstituting data by dividing the output of the low resolution codingmeans and the differential component coding means into predeterminedareas for adding an error correction codes. When the picture datathinned in space is coded so that only this coded data is accessed, thepicture data can be coded so that the scene can be sufficientlyunderstood when the picture is decoded. The decoded data from the lowresolution coding means is interpolated thereby obtaining a differentialcomponent by comparing the picture with the picture before the lowresolution conversion with the result that the picture data of the highresolution portion which cannot be obtained by low resolution codingmeans is coded. Thus the picture information other than the lowresolution degree can be coded.

Still another digital video signal playback device of the presentinvention synthesizes the data of the low resolution component with thedata of the differential component to be decoded. At the time of thenormal playback, the coded data of the low resolution component and thecoded data of the high resolution component which is the differentialcomponent between the low resolution portion and the data before beingthinned into a low resolution are synthesized so that a picture with acomplete resolution component can be decoded.

In the aforementioned digital video signal playback device of thepresent invention, a mode of decoding a picture by synthesizing the dataof a low resolution component with the data of the differentialcomponent is switched over with a mode of decoding only the lowresolution component. At the time of the normal playback, a lowresolution coded data segmented into two is synthesized with the codeddata of a high resolution component which is a differential componentbetween data before being thinned to a low resolution and the data ofthe low resolution portion are synthesized so that a picture with acomplete resolution can be decoded. At the time of the special playback,a decoding mode is switched over in accordance with the operating stateof the device so that a rough picture can be decoded by decoding onlythe coded data of low resolution.

In the aforementioned digital video signal playback device, when the lowresolution picture is decoded, only the picture interpolated afterdecoding is generated. At the time of the special playback, when onlythe coded data of low resolution is decoded, the video data of the lowresolution component is interpolated to bring back the size of thepicture to the original size thereof.

Still another digital video signal record device of the presentinvention includes judging means for judging the degree of picturedeterioration at the time of coding and decoding on a basis of themotion compensation prediction and the orthogonal transform, adaptivecoding means for coding a data rate by adaptively changing the rate onthe basis of the judgment output from the judging means, informationadding means for adding an audio signal, additional information such asheader or the like, and error correction code, and a data rate settingmeans for setting a discrete value for the adaptively changed data rate.In the coding means for a variable rate, the rate is limited only to alimited value. Consequently, the data rate information of the GOP (whichcorresponds to the code amount of the GOP) can be represented with asmall number of bits.

Still another digital video signal record device of the presentinvention includes judging means for judging the degree of picturedeterioration at the time of coding and decoding on the basis of themotion compensation prediction and the orthogonal transform, adaptivecoding means for coding a data rate by adaptively changing the rate onthe basis of the judgment output from the judging means, informationadding means for adding an audio signal, additional information such asheader or the like, and error correction code, wherein the device is soconstituted that data rate information is multiplexed on the head or thelike, or is written in a predetermined area on the recording medium. Thedata rate set information in the case where the picture data is coded ata variable rate is recorded on the recording medium apart from the videodata. Consequently, the data rate information can be read in summary sothat information can be recorded which allows immediate recording of theposition of the predetermined GOP which occupies a disc.

Still another digital video signal record device includes judging meansfor judging the degree of picture deterioration at the time of codingand decoding on the basis of the motion compensation prediction and theorthogonal transform, information adding means for adding an audiosignal, additional information such as header or the like, and errorcorrection code, first coding means for coding a video signal thinned ata predetermined interval with respect to a video signal comprising acoded picture including a picture subjected to the intra-frame coding,second coding means for coding with respect to the remaining componentby coding using the first coding means out of the video signal, whereinthe device is so constituted that the data rate at least in either ofthe coding means out of the first or the second coding means isadaptively changed and coded on the basis of a judgment output from thejudging means. A high quality coding can be realized by the variablerate. In the GOP in which the rate has largely increased, the video datathinned in space is coded and coding can be performed so that the areawhich is accessed at least is decreased.

Still another digital video signal record device of the presentinvention includes judging means for judging the degree of picturedeterioration at the time of coding and decoding on the basis of themotion compensation prediction and the orthogonal transform, informationadding means for adding an audio signal, additional information such asheader or the like, and error correction code, first coding means forcoding only a low frequency area orthogonally transformed with respectto a video signal comprising a coded picture including a picturesubjected to the intra-frame coding, second coding means for coding withrespect to the remaining component by coding the signal using the firstcoding means out of the video signal, wherein the device is soconstituted that the video signal is coded by adaptively changing thedata rate in at least either of the coding means out of the first codingmeans or the second coding means on the basis of the judgment outputfrom the design judging means. A high quality coding can be realizedwith the variable rate. With the GOP in which the rate has largelyincreased, the video data in a partial frequency area is coded for eachblock, and the coding can be performed so that the area accessed atleast is decreased.

Still another digital video signal record device includes judging meansfor judging the degree of picture deterioration at the time of codingand decoding on the basis of the motion compensation prediction and theorthogonal transform, information adding means for adding additionalinformation such as an audio signal, a header or the like and an errorcorrection code, first coding means for coding a video signal through arough quantization on a quantization level with respect to a videosignal comprising a coded picture including a picture subjected to theintra-frame coding, second coding means for coding with respect to theremaining component by coding the signal using the first coding meansout of the video signal, wherein that the video signal is coded byadaptively changing the data rate in at least either of the coding meansout of the first coding means or the second coding means on the basis ofthe judgment output from the design judging means. A high quality codingcan be realized with a variable rate. In the GOP in which the rate haslargely increased by the variable rate, the data in the upper bit whichdeeply affects the picture is coded, and the coding can be performed sothat the area accessed at least is decreased.

Still another digital video signal playback device of the presentinvention switches over a playback mode between the normal playback modeand the special playback mode thereby extracting data rate information.At the time of the special playback mode, the position of the recordingmedium where data for the special playback exists is calculated on thebasis of the data rate information at the time of the special playbackmode. When the GOP with a different data rate is played back byextracting the data rate information of each GOP, the coded data dividedinto two are synthesized and decoded at the time of the normal playback.At the time of the special playback, the position of the GOP on therecording medium which is to be accessed is calculated. Then, the datato be accessed at least is played back to access the next target GOP. Atthis time, the position information on the recording medium where theGOP to be accessed is calculated to facilitate the special playback andretrieval of a high quality variable rate.

In the aforementioned digital video signal playback device, a headposition is controlled to a position on the recording medium dependingon the result of the position calculation and the special playback rate.The position information on the disc where the GOP which constitutes theaccess target is calculated on the basis of the special playback rate.The position of the optical head can be controlled to the position ofthe target GOP depending on the special playback rate so that a highquality variable rate can be played back in a special mode at variety ofspeed.

With still another digital video signal record device of the presentinvention, a code amount is controlled corresponding to an area assignedto one picture group which is formed by the digital video signal codedon the basis of the motion compensation prediction and the orthogonaltransform, and the device of the present invention includes coding meansfor coding, code amount comparing means for comparing an output from thecoding means with a predetermined amount of data, and a data feedingmeans for embedding superfluous data in a blank area of picture groupshaving the blank area. In the case where the data is coded and recordedat a variable rate, the access time can be shortened by locating the GOPat a position wherein the head is easily accessed so that the data iscoded and recorded increasing the read data amount in the specialplayback. Further, unnecessary parts such as blank parts on the disc atthat time can be filled as much as possible thereby using such parts forthe improvement in the picture quality or contributing to the extensionof the recording time by those parts.

Still another digital video signal playback device of the presentinvention includes data reconstructing means for reconstructing embeddedvideo signal coded data into original group of pictures, and datadecoding means for decoding data reconstructed by data reconstructingmeans. A coded data in which other GOP data is embedded in a blank partcan be reconstructed so that the data can be decoded without distortion.Further, the data amount still increases at the time of the specialplayback, and a high quality playback picture can be still obtained.

Still another digital video signal playback device of the presentinvention switches over on the basis of the special playback speed as towhich of the three decoding means, first decoding means for decoding afirst and second coded data and obtaining a playback picture, a seconddecoding means for decoding the first coded data and obtaining theplayback picture which corresponds to the low frequency region of thepicture subjected to the intra-frame coding, the number of pixelsthinned out or a rough quantization, and a third decoding means fordecoding the first coded data and obtaining a playback picturecorresponding to the low frequency region of the intra-frame codedpicture and the inter-frame prediction picture, the number of pixelsthinned out, or the rough quantization. Since the mode is switched overbetween a mode of decoding and displaying only the I picture and themode of displaying the I picture and the P picture, the special playbackof the I picture and the P picture can be realized at a relatively slowspecial playback (for example, a double-speed playback) with the resultthat a fine special playback free from frame jumping can be realizedcompared with the special playback of only the I picture. Further, atthe time of the special playback at a high speed, various playbackspeeds can be treated such as the special playback of the I picture.

Still another digital video signal playback device of the presentinvention includes video data extracting means for extracting datacorresponding to the video signal from the playback code, picture datadecoding and playback means for decoding and playing back the video dataoutputted from the video data extracting means, and mode switching meansfor switching a normal playback mode, a mode for playing back anddisplaying either an odd number field or an even number field, and amode for displaying either the odd number field or an even number fieldby reversing the field structure thereof. At the time of the specialplayback, the field structure is optimized depending on the mode. At thetime of the reverse playback, the display is given so that the device isoperated in a reverse manner until the field display. At the time of theplayback of the frame jumping such as fast winding or the like, aspecial playback picture can be obtained which is easy to watch byoutputting the same video picture both in the even number field and inthe odd number field to set the number of fields to a definite level.

The above and further objects and features of the invention will morefully be apparent from the following detailed description withaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a conventional optical disc record andplayback device.

FIG. 2 is a block diagram of a video signal coding unit in aconventional MPEG.

FIG. 3 is a block diagram of a conventional motion compensationpredicting circuit.

FIG. 4 is a block diagram of a video signal decoding unit in theconventional MPEG.

FIG. 5 is a view showing a data arrangement structure of a video codingalgorithm of the conventional MPEG.

FIG. 6 is a view showing an example of a GOP structure of a video codingalgorithm of the conventional MPEG.

FIGS. 7A and 7B are views showing one example of a video bitstream ofthe conventional MPEG.

FIG. 8 is a view showing an example of a system stream in the PS in theconventional MPEG.

FIG. 9 is a view showing an example of a PES packet stream of theconventional MPEG.

FIG. 10 is a block diagram of the conventional digital signal record andplayback device.

FIG. 11 is a block diagram of a video signal coding unit in theconventional digital video signal record and playback device.

FIG. 12 is a block diagram of a video signal decoding unit in theconventional digital video signal record and playback device.

FIGS. 13A and 13B are views illustrating a concept of mobile pictureprocessing in the conventional digital signal record and playbackdevice.

FIG. 14 is a block diagram of a video signal coding unit in theconventional digital signal record and playback device.

FIG. 15 is a block diagram of a record system in a digital signal recordand playback device according to embodiment 1.

FIG. 16 is a block diagram of a playback system in the digital recordand playback device according to embodiment 1.

FIG. 17 is a conceptual view for illustrating macro blocks.

FIG. 18 is a conceptual view for illustrating a screen division.

FIG. 19 is a conceptual view for illustrating a data arrangement.

FIGS. 20A through 20D are conceptual views for illustrating a playbackmethod in a special playback.

FIGS. 21A and 21B are conceptual views for a method for performing thespecial playback in the case where the data is extended.

FIG. 22 is a conceptual view for illustrating a screen divisionaccording to embodiment 3.

FIG. 23 is a conceptual view for illustrating a data arrangementaccording to embodiment 3.

FIGS. 24A through 24E are conceptual views for illustrating a method forperforming the special playback according to embodiment 3.

FIGS. 25A and 25B are conceptual view for illustrating an errorcorrection block arrangement according to embodiment 3.

FIGS. 26A through 26D are conceptual views for illustrating a method forperforming the special playback according to embodiment 4.

FIGS. 27A through 27F are conceptual views for illustrating a method forperforming the special playback in the case where the data interpolationin embodiment 4 is performed.

FIGS. 28 is a conceptual view for illustrating a data arrangement inembodiment 5.

FIGS. 29A through 29E are conceptual views for illustrating a playbackmethod in a special playback according to embodiment 5.

FIG. 30 is a conceptual view for illustrating a data arrangement inembodiment 6.

FIGS. 31A through 31F are conceptual views for illustrating a method forperforming the special playback in embodiment 6.

FIGS. 32A and 32B are conceptual views for illustrating an errorcorrection block arrangement in embodiment 6.

FIGS. 33A through 33G are conceptual views for illustrating a playbackmethod in embodiment 7.

FIGS. 34A through 34F are conceptual views for illustrating a method forperforming the special playback in the case where the data interpolationin embodiment 7 is performed.

FIG. 35 is a conceptual view for illustrating data arrangement inembodiment 8.

FIG. 36A through 36F are conceptual views for illustrating a method forperforming the special playback in embodiment 8.

FIG. 37 is a block diagram of a digital video signal coding unit inembodiment 9.

FIG. 38 is a view showing a concept of a frequency division inembodiments 9 and 11.

FIG. 39 is a flowchart of a digital video signal coding processing inembodiment 9.

FIG. 40 is a view for illustrating a header in a bitstream in embodiment9.

FIGS. 41A through 41D are views showing rearrangement of the bitstreamin embodiment 9.

FIG. 42 is a view showing an example of address information of a systemstream in embodiment 9.

FIG. 43 is a block diagram of a digital video signal decoding unit inembodiment 9.

FIG. 44 is a view showing a concept of decoding processing in embodiment9.

FIG. 45 is a flowchart of decoding processing in embodiment 9.

FIG. 46 is a block diagram of a digital video signal coding unit inembodiment 10.

FIG. 47 is a block diagram of a digital video signal decoding unit inembodiment 10.

FIG. 48 is a view showing an example of an area of a screen inembodiment 10.

FIG. 49 is a view showing an example of a bitstream when the video datais rearranged in the unit of area of the screen in embodiment 10.

FIG. 50 is a flowchart of a digital video signal coding processing inembodiment 10.

FIG. 51 is a view showing an example of address information of a systemstream in embodiment 10.

FIG. 52 is a view showing an example of a system stream in embodiment10.

FIGS. 53A through 53E are views showing an example of a playback screenin which the picture can be played back at the time of the playback.

FIGS. 54A through 54B are views showing an example of the playbackscreen in embodiment 10 wherein only the central part of the screen isoutputted at the time of the playback.

FIGS. 55A and 55B are views showing an example the playback screen inembodiment 10 in which an area in the central part of the screen ismagnified and displayed.

FIG. 56 is a flowchart of a digital video decoding processing inembodiment 10.

FIG. 57 is a block diagram of a digital signal coding unit in embodiment11.

FIG. 58 is a flowchart of a digital video signal coding processing inembodiment 11.

FIGS. 59A through 59D are views showing an example of a system stream inembodiment 11.

FIG. 60 is a view showing an example of address information of thesystem stream in embodiment 11.

FIG. 61 is a block diagram of a digital video signal decoding unit inembodiment 11.

FIG. 62 is a flowchart of a digital video signal decoding processing inembodiment 11.

FIG. 63 is a block diagram of a digital video signal coding unit inembodiment 11.

FIG. 64 is a view showing a concept of a resolution conversion inembodiment 12 on the screen.

FIG. 65 is a view illustrating one example of data constitution resultsin embodiments 12, 13 and 14.

FIG. 66 is a block view of a digital video signal coding unit inembodiment 13.

FIG. 67 is a view illustrating one example of a data arrangement of aDCT coefficient inside of a DCT block.

FIG. 68 is a block diagram of a digital video signal coding unit inembodiment 14.

FIG. 69 is a view illustrating an example of the statistical amount ofcoded data in embodiments 12, 13 and 14.

FIG. 70 is a view showing one example of a processing sequence inembodiments 12, 13 and 14.

FIGS. 71A through 71D are views illustrating one example of arrangementoutline of a frequency component in a bitstream of the DCT block inembodiment 15 and in one block.

FIG. 72A is a block diagram of a digital video signal decoding unit inembodiment 15.

FIG. 72B is a view illustrating an operation concept of a digital videosignal decoding processing in embodiment 15.

FIG. 73A is a block diagram showing a digital video signal coding unitin embodiment 16.

FIG. 73B is a view illustrating an operation concept of a digital videosignal coding processing in embodiment 16.

FIG. 74 is a block diagram of a digital video signal decoding unit inembodiment 16.

FIG. 75 is a block diagram of a digital video signal decoding unit inembodiment 17.

FIG. 76 is a block diagram of a GOP address generator and a disccontroller in embodiment 18.

FIG. 77 is a block diagram of a GOP address generator and a disccontroller including a playback processing in embodiment 18.

FIG. 78 is a block diagram of a digital video signal decoding unit whenthe division by the frequency and the division by the quantization inembodiment 19 are performed.

FIG. 79 is a block diagram of the digital video signal decoding unitwhen the division by the bit length in embodiment 19 is performed.

FIG. 80 is a block diagram of the digital video signal decoding unitwhen the division by the resolution in embodiment 19 is performed.

FIG. 81 is a block diagram of the digital video signal coding unit inembodiment 20.

FIG. 82 is a block diagram of the digital video signal decoding unit inembodiment 20.

FIGS. 83A and 83B are views illustrating a concept of the processingwith the digital video signal record and playback device in embodiment20.

FIG. 84 is a block diagram of the digital video signal decoding unitwhen the division by the frequency or the division by the quantizationin embodiment 21 is performed.

FIG. 85 is a block diagram of the digital video signal decoding unitwhen the division by the bit length or the division by the quantizationin embodiment 21 is performed.

FIG. 86 is a block diagram of a digital video signal decoding unit whenthe division by the resolution or the division by the quantization inembodiment 21 is performed.

FIG. 87 is a block diagram of the digital video signal decoding unitwhen the division by the frequency or the division by the quantizationin embodiment 22 is performed.

FIG. 88 is a block diagram of the digital video signal decoding unitwhen the division by the bit length or the division by the quantizationin embodiment 22 is performed.

FIGS. 89A and 89B are views showing the concept of processing at thetime of skip search in embodiment 22.

FIGS. 90A and 90B are views showing a concept of processing at the timeof the inverse playback in embodiment 22.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will de explained in detail on the basis of thedrawings showing embodiments.

Embodiment 1

Embodiment 1 of the present invention will be explained. FIG. 15 is ablock circuit diagram showing a recording system of a digital videosignal record and playback device in embodiment 1. Referring to FIG. 15,a digital video signal outputted from an input terminal 1 is inputted toa formatting circuit 3. The video signal which is outputted from theformatting circuit 3 provided as to a first input of a subtracter 4 anda second input of a motion compensation predicting circuit 11. An outputof the subtracter 4 is inputted to a quantizer 6 via a DCT circuit 5. Anoutput of the quantizer 6 is provided as a first input of a buffermemory 12 via a variable-length encoder 7. In the meantime, the outputof the quantizer 6 is also provided as an inverse DCT circuit 9 via aninverse quantizer 8. An output of the inverse DCT circuit 9 is given toa first input of an adder 10.

An output of the adder 10 is provided as a first input of the motioncompensation predicting circuit 11. A first output of the motioncompensation predicting circuit 11 is provided as a second input of theadder 10 and a second input of the subtracter 4. Further, a secondoutput of the motion compensation predicting circuit 11 is provided as asecond input of the buffer memory 12. An output of the buffer memory 12is inputted to a modulator 14 via a format encoder 13. An output of themodulator 14 is recorded on a recording medium such as an optical discor the like via an output terminal 2.

FIG. 16 is a block circuit diagram showing a playback system in thedigital video signal record and playback device according toembodiment 1. Referring to FIG. 16, video information read from therecording medium is inputted from an input terminal 20 to a demodulator21. An output from the demodulator 21 is inputted to the format decoder23 via a buffer memory 22. The first output of a format decoder 23 isinputted to a variable-length decoder 24, and inversely quantized by aninverse quantizer 25. Then the output is subjected to an inverse DCT atan inverse DCT circuit 26 to be provided as the first input of an adder28. In the meantime, the second output of the format decoder 23 isinputted to a prediction data decoding circuit 27. Then, the output fromthe prediction data decoding circuit 27 is given to the second input ofthe adder 28. The output of the adder 28 is outputted from an outputterminal 30 via an unformatting circuit 29.

Next, operation of the device will be explained. The digital videosignal is inputted from the input terminal in units of lines, and issupplied to the formatting circuit 3. Here, in the motion compensationprediction, one GOP is set to 15 frames as shown in FIG. 6 as in theconventional example to perform prediction coding with one frame of Ipicture, 4 frames of P pictures (P1 through P4), and ten frames of Bpictures (B1 through B10). In this case, in the formatting circuit 3,the video data inputted in a consecutive manner is rearranged andoutputted in the units of frames in the order shown in FIG. 7.

Further, the data inputted in the units of lines is rearranged in theunits of blocks of 8×8 pixels so that macroblocks (six blocks in total,such as adjacent four luminance signal Y blocks and two color differencesignals Cr and Cb blocks which correspond in position to the Y block) isconstituted. The data is outputted in units of macroblocks. Here, themacroblocks are determined in the minimum unit of the motioncompensation prediction while the motion vector for the motioncompensation prediction is determined in the units of macroblocks.

Further, with the formatting circuit 3, with respect to the I picture,one frame of video data is divided into three areas so that blocking isperformed in this area in the unit of 8×8 pixels and the macroblock isconstituted and outputted. Here, the three divided areas are set asareas 1, 2 and 3 from the top of the screen as shown in FIG. 18. In FIG.18, the area 2 located at the central part of the screen has a size of720 pixels×288 lines while the areas on both ends of the screen have asize of 720 pixels×96 lines. In the meantime, in the P picture and the Bpicture, the blocking is performed without being divided into each areaand is outputted in the units of macroblocks.

An output of the formatting circuit 3 is inputted to the subtracter 4and the motion compensation predicting circuit 11. The operation of thesubtracter 4, the DCT circuit 5, the quantizer 6, the variable-lengthencoder 7, the inverse quantizer 8, the inverse DCT circuit 9, the adder10 and the motion compensation predicting circuit 11 is the same as theconventional embodiments, and the explanation thereof is omitted.

The video-data outputted from the variable length encoder 7 and themotion vector outputted from the motion compensation predicting circuit11 are inputted to the buffer memory 12. In the buffer memory 12, thevideo data and the motion vector for one GOP portion are recorded andthe data is subsequently outputted in sequence to the format encoder 13.The output of the format encoder 13 is inputted to the modulator 14 andan error correction codes or the like are added and recorded on therecording medium such as an optical disc or the like.

In the format encoder 13, the video data for the one GOP portion isrearranged in the data arrangement as shown in FIG. 19 and is outputtedto the modulator 14. Here, the I picture is divided into three areas asshown in FIG. 18. When the data of the I picture corresponding to theseareas 1 through 3 are set to I(1), I(2) and I(3), the data of the Ipicture is constituted so that the data is recorded in the order ofI(2), I(1) and I(3) at the front part of the data string of one GOPportion.

Further, the address where the data of each picture area is stored atthe front of the GOP is recorded as header information. The number ofbytes which is occupied in the data format shown in FIG. 19 by the datain each area divided into three parts is recorded as header information.Consequently, depending on the number of bytes occupied by each areawhich is recorded in the header information, the end position of eacharea can be recognized as a relative address from the front of the GOPat the time of playback. Consequently, the optical head jumps to thefront address of the GOP in the unit of the definite time at the time ofthe special playback so that data can be read in each area in accordancewith the header information from the front of the GOP.

With a general video signal record and playback device, on the dataformat at the time of data recording, the I picture is recorded in theunits of frames. In contrast, in FIG. 19, a priority is given to an arealocated at the central part of the screen out of the I picture datawhich is divided into three parts so that the area is located at thefront of one GOP. Consequently, in the case where only a part of thearea of the I picture can be decoded in a definite time at the time of ahigh speed playback, at least the playback picture at the central partof the screen can be outputted.

Subsequently, operation at the time of playback will be explained inaccordance with FIG. 16. The demodulator 21 performs error correctionprocessing so that the video signal recorded in a format shown in FIG.19 in the buffer memory 22 is divided into the motion vector and thevideo data at the format decoder 23 to be outputted to the predictingdata decoding circuit 27 and the variable-length decoder 24,respectively. Here, an operation at the time of the normal playback isthe same as the conventional embodiment, and an explanation thereof isomitted.

At the time of a high speed playback, with respect to the data recordedin one GOP unit on the recording medium such as an optical disc or thelike, the optical head jumps to the front of the one GOP in the unit ofdefinite time so that the data part of the I picture is read in units ofareas in accordance with the header information recorded at the front sothat the data is demodulated at the demodulator 21 and is input to thebuffer memory 22. Here, in the case where data is read from therecording medium such as an optical disc or the like at the time of ahigh speed playback, waiting time for the disc rotation arises at thetime of jumping to the front of the GOP even when the front address ofthe GOP which is recorded on the disc is known. Consequently, when thehigh speed playback speed is increased, the time for reading the data onthe disc becomes short. Since the waiting time for the disc rotationvaries, it becomes impossible to read all the I picture data in a stablemanner.

Consequently, when the high speed playback speed is increased, afteronly the data of the area 2 located at the central part of the screen isread the optical head jumps to the front of the subsequent GOP so thatonly the data in the area 2 that can be read is inputted to the buffermemory 22. In this case, the format decoder 23 decodes only the area 2of the I picture that can be read. On the other hand, the areas 1 and 3whose data are not read are masked by the gray data, and a high speedplayback picture is outputted. Consequently, in the case where one GOPis set to 15 frames, a 15 times speed special playback picture can beobtained.

FIG. 20 shows a playback picture in the case where a high speed playbackis performed by playing back only the area 2 of the I picture from thenth GOP of one COP up to the n+3th GOP. In FIG. 20, the areas 1 and 3 onboth ends of the screen in FIG. 20 are masked by the gray data. Further,when the information amount of the I picture is small and the discrotation wait time is short, and time is available for reading data inthe areas 1 and 3, the data of the areas 1 and 3 is not decoded. This isbecause all the data of one screen portion cannot be read in a stableway at the time of a high speed playback, and if a screen is outputtedonly when the data in the areas 1 and 3 can be read, these areas cannotbe outputted in a definite interval so that a high speed playbackpicture becomes unnatural.

As described above, since the I picture used for the special playback asshown in FIG. 19 is arranged so that a priority is given to the arealocated in the center of one screen is recorded on the recording mediumat the front of G82 one GOP, only the data of the area 2 located at thecenter is read for a high speed play back even when the high speedplayback speed is increased with the result that the content of theplayback picture is easy to see. Further, since only the data in theregion of the area 2 is read from the recording medium, a higher speedspecial playback can be realized compared with a case in which the wholeI picture is read.

In, the aforementioned embodiment 1, the I picture is divided into threeareas in the vertical direction as shown in FIG. 18 and is recorded, thepicture is not necessarily divided into three areas. The area may bedivided into n areas (n>1) in the unit of slice defined in theinternational standard MPEG for recording the data. Here, the slice hasa one dimension structure of macroblocks of a arbitrary number oflengths (one or more) so that when the right end of the screen isattained, the display continues to the left end one line below.

Embodiment 2

Next, embodiment 2 of the present invention will be explained withrespect to the figures. FIG. 21 is a conceptual view for explaining amethod for special playback in the case where data extension inembodiment 2 is performed. In embodiment 1, the I picture is dividedinto three areas as shown in FIG. 18 so that only the data of the area 2located at the center of the area is read and played back. Thus, withrespect to the areas 1 and 3, the mask data is outputted. However, thedata of the area 2 is extended to a size of one screen as shown in FIG.21.

In this case, at the time of converting the video signal into data inunits of lines with the unformatting circuit 29, the data of the area 2is interpolated to be extended to a size of one screen portion and isoutputted. In the case of FIG. 21, the area 2 has a size of 720pixels×288 lines and is constituted in 144 line symmetric in verticaldirections from the center of the screen.

Here, at the time of the special playback, when the upper half part ofthe area 2 is set to AR2 a and the lower half part is set to AR2 b asshown in FIG. 21A, AR2 a and AR2 b are extended by 1.5 times in thevertical direction respectively to synthesize playback pictures AR2 a′and AR2 b′ as shown in FIG. 21B. With respect to the method forextending the pictures, when the data in the unit of each line of AR2 ais defined as AT(l)(l: line number 1≦l≦144), and line data in the upperhalf part of the extended screen is set to DT(m) (1≦m≦240), extension ismade which is represented by the following expressions.DT(3n−2)=AT(2n−1)DT(3n−1)=AT(2n−1)DT(3n)=AT(2n)(n=1 to 80)

In the meantime, when the data in the unit of each line of AR2 b isdefined as AB(l) (l: line number l≦l≦144), and line data in the lowerhalf part of the extended screen is set to DB(m) (1≦m≦240), extension ismade which is represented by the following expressions.DB(3n−2)=AB(2n−1)DB(3n−1)=AB(2n−1)DB(3n)=AB(2n)(n=1 to 80)

As described above, only the data of the area 2 located at the center ofscreen at the time of the high speed playback is read and is extended toa size of one screen portion and is outputted as a playback picture.Consequently, since both ends of the playback picture at the time of ahigh speed playback is not masked, the playback picture cease to befavorable to watch.

In the aforementioned embodiment 2, the screen is extended in thevertical direction by inserting data simply in units of lines. The linedata may be linearly interpolated with respect to the verticaldirection.

Embodiment 3

Embodiment 3 of the present invention will be explained. A structure ofa recording system and a playback system of the digital video signalrecord and playback device in embodiment 3 is the same as embodiment 1(see FIGS. 15 and 16).

Next, an operation of the device will be explained. A digital videosignal is inputted in units of lines from the input terminal 1 and issupplied to the formatting circuit 2. Here, in the motion compensationprediction, one GOP is set to 15 frames like the conventional example asshown in FIG. 6. Then, the GOP is subjected to the prediction coding asone frame of I picture, four frames of P pictures (P1 through P4), 10frames of B pictures (B1 through B10). In this case, in the formattingcircuit 3, the video data, inputted in a continuous manner like theconventional example, is rearranged in the unit of frame in an order asshown in FIG. 7 and is outputted. Further, the data inputted in units oflines is rearranged in units of blocks having 8×8 pixels to constitute amacroblock (a total of six blocks of adjacent four luminance signal Yblocks and two color difference signals Cr and Cb blocks) shown in FIG.17 so that data is outputted in the units of macroblocks. Here, themacroblock is the minimum unit of the motion compensation prediction,and the motion vector for the motion compensation prediction isdetermined in units of macroblocks.

Further, in the formatting circuit 3, the I picture is divided into fiveareas for each of 720 pixels×96 lines in the vertical direction of oneframe of video data. In this area, 8×8 pixels are blocked to constitutea macroblock for the output. In this case, divided five areas aredefined as areas 1, 2, 3, 4 and 5. In the meantime, the P picture andthe B picture are blocked without being divided into areas and areoutputted in units of macroblocks.

The output of the formatting circuit 3 is inputted to the subtracter 4and the motion compensation predicting circuit 11, but the operation ofthe subtracter 4, the DCT circuit 5, the quantizer 6, the variablelength encoder 7 and the inverse quantizer 8, the inverse DCT circuit,the adder 10, and the motion compensation predicting circuit 11 is thesame as the conventional embodiment and an explanation thereof isomitted.

The video data outputted from the variable-length encoder 7 and themotion vector outputted from the motion compensation circuit 11 areinputted to the buffer memory 12. In the buffer memory 12, the videodata and the motion vector of one GOP portion is recorded, and the datais outputted to the format encoder 13 in sequence. The output of theformat coder 13 is inputted to a modulation circuit 14 so that an errorcorrection code or the like is added and is recorded on the recordingmedium such as an optical disc or the like.

In the format encoder 13, the data of the GOP portion is outputted tothe modulator 14 by rearranging the video signal in the data arrangementas shown in FIG. 23. The I picture are divided into five areas as shownin FIG. 22 so that the data of the I picture corresponding to areas 1through 5 are defined as I(1), I(2), I(3), I(4) and I(5). In FIG. 23,the data of the I picture is constituted to be recorded in the order ofI(3), I(2), I(4), I(1) and I(5) at the front of a data stream for oneGOP so that priority is given to the area which comes to the center ofthe screen.

Further, in FIG. 23, the address where the data of each I pictures isstored is written as header information. As the header information, thenumber of bytes which the data in each area occupies on the data formatis recorded, the area being obtained by dividing the I picture into fiveparts. Consequently, at the time of the playback, it is possible torecognize the end position of each area as a relative address withrespect to the front of the GOP on the basis of the number of bytesoccupied by each area which is recorded in header information at thetime of the playback. As a consequence, the optical head jumps to thefront address of the GOP in the unit of a definite time so that the dataof the I picture can be read in the unit of area in accordance with theheader information from the front of the GOP.

With a general video signal record and playback device in common use, inthe data format at the time of recording, the I picture is recorded inunits of frames. In contrast, in FIG. 23, a priority is given to an arealocated at the central part of the screen out of the five areas obtainedby dividing the I picture to be arranged at the front of one GOP withthe result that the playback picture at least at the central part of thescreen can be outputted even in the case where only the area in part ofthe I picture can be decoded.

Subsequently, an operation at the time of playback will be explained inaccordance with FIG. 16. A video signal which is subjected to an errorcorrection processing in the demodulator 21 and is recorded in a formatof FIG. 23 in the buffer memory 22 is divided into the motion vector andthe video data which are outputted to the prediction data decodingcircuit 27 and the variable-length decoder 24, respectively. Here, theoperation at the time of the normal playback, is the same as theconventional embodiments, a detailed explanation thereof is omitted.

At the time of a high speed playback, with respect to the data recordedon the recording medium such as an optical disc or the like, the opticalhead jumps to the front of the GOP in the unit of a definite time toread the data part of the I picture in accordance with the headerinformation and the data is demodulated at the demodulator 21 to beinputted to the buffer memory 22. However, in the case where theinformation amount of the I picture is too large to be read in adefinite time, the data which has been half read is read to the lastitem of the data, and the optical head jumps to the front of thesubsequent GOP to input only the data that can be read into the buffermemory 22. In such a case, in the format decoder 23, only the area ofthe I picture that can be read is decoded and is outputted as a highspeed playback picture. Consequently, when one GOP is set to 15 frames,a 15 times speed special playback picture can be obtained.

FIG. 24 shows a playback picture in the case where only the I picture ofone GOP is played back. In this case, the information amount of allareas of the I pictures is too large to be read from the recordingmedium, with respect to the area which cannot be read, data of thepreceding area is held as they are to be outputted thereby synthesizingthe high speed playback picture. In FIG. 24, in the case where the n+1thGOP area 5 and n+3th GOP areas 1 and 5 cannot be read, the playbackpicture immediately before the playback picture is held as it is.

In this manner, the I picture used in the special playback as shown inFIG. 23 is positioned so that the priority is given to the area locatedat central part of the screen just above the screen to be recorded onthe recording medium at the front of one GOP. Thus even when the whole Ipictures cannot be read, the central part of the screen is given apriority in playback so that the content of the playback picture is easyto understand.

In the aforementioned embodiment 3, when the whole I pictures cannot beread, the playback picture is interpolated in units of areas, theinterpolation may not be made in units of areas, but may be made inerror correction block.

In this case, the demodulator 21 segments data into several byte-longpackets with respect to the data arrangement shown in FIG. 23, and aerror correction code is added to each packet. FIG. 25 shows an exampleof a case in which data in five areas inputted in a consecutive manneris divided into packets in error correction block units. FIG. 25A showsa data string before the packet division. FIG. 25B shows data after thepacket division. Five areas of the I picture are divided into packetswith a definite volume and the area I(3) is divided into packets from 1through I and the I(4) is divided into packets I through j for theinput.

At the time of a high speed playback, the optical head jumps to thefront of the GOP in the unit of a definite time with respect to datarecorded on the recording medium such as an optical disc or the like inthe unit of GOP to read the data portion of the I picture in the unit ofarea in accordance with the header information. The data portion isdemodulated by the demodulator 21 to be inputted to the buffer memory22. However, in the case where the whole I picture cannot be read in adefinite time because the information amount of the I picture is large,the optical head jumps to the front of the subsequent GOP even when theone area portion of data is being read. Further, data which can be readis subjected to the error correction processing so that the data whichcan be error corrected is inputted to the buffer memory 22. In thiscase, the format decoder 23 recognizes an address of the I picture areawhich can be decoded to the midway so that the data which can be read isdecoded in units of macroblocks and is outputted as a high speedplayback picture. In this case, with respect to the macroblock whichcannot be decoded, data of the preceding screen is held and outputted asit is.

In the aforementioned embodiment 3, data in each area of the I pictureis divided into packets in a consecutive manner. However, data may bedivided so that the data in two or more areas may not be included in onepacket. In this case, data in one area portion is closed in integertimes of the error correction block with the result that the data can berearranged in the unit of area immediately after the error correctionprocessing. When data in each area is divided into the unit of packet,data is inputted halfway to the last packet of each area so that theresidual data is required to be placed in data masking (for example, allthe data is masked to “1”).

In addition, in the aforementioned embodiment 3, a priority is given inthe order of 3, 2, 4, 1 and 5. However, the order is not limited to thisorder. The order may be, for example, 3, 4, 2, 5 and 1.

In addition, in the aforementioned embodiment 3, the I picture isdivided into five areas in the horizontal direction and recorded asshown in FIG. 22. The data is not required to be divided into fiveareas, but the data may be divided into n areas (n>1) in the unit ofslice defined by the international standard MPEG. Here, the slice has aone dimensional structure of macro blocks with an arbitrary number oflengths (one or more). The slice is a belt which continues to the leftend one line below upon reaching the right end of the screen.

Embodiment 4

Next, embodiment 4 of the present invention will be explained withrespect to the figures. FIG. 26 is a view showing a special playbackmethod in embodiment 4. In embodiment 3, a special playback is performedwith a playback method shown in FIG. 24. However, the special playbackmay be performed so that the playback picture as shown in FIG. 26 isoutputted. In this case, the format decoder 23 synthesizes one screen byplaying back each one area from the I pictures of five GOP's which arecontinuous as shown in FIG. 26. For example, in FIG. 26A, one screenportion of the playback picture is synthesized from the I pictures ofnth to the n+4^(th) GOP so that the I picture of the n+4^(th) GOP isplayed back in area 1, the I picture of the n+3th GOP is played back inarea 2, the I picture of the n+2th GOP is played back in area 3, the Ipicture of the n+1th GOP is played back in area 4, and the I picture ofthe nth GOP is played back in area 5. Further, referring to FIG. 26,when an attention is paid to the area 5, the I picture of the nth,n+1th, n+2th - - - GOP are played back as the played back video data.

Further, when the whole I picture cannot be read during a definite timebecause the information amount of the I picture is large, the datapreceding by one screen is held as it is and is outputted to synthesizea higher speed playback picture. FIG. 27 is a playback picture when then+1th GOP area 5, and n+3th GOP areas 1 and 5 cannot be read. In thiscase, since the data arrangement is recorded on the recording medium bygiving a priority to the an area located at the central part of thescreen as shown in FIG. 23, the central portion of the screen is given apriority in the playback even in the case where the whole I picturecannot be read in terms of time with the result that it never happensthat the playback picture is hard to see. Further, even in the casewhere data in two or more areas cannot be read, one screen is dividedinto five areas. Since the frame played back in each area is different,it is hard to detect that data is lacking in the playback picture.

Embodiment 5

Next, embodiment 5 of the present invention will be explained withrespect to the figures. FIG. 28 is a view showing an arrangementstructure of a digital video signal data according to embodiment 5. Inembodiment 3, the data arrangement is written in the order of the areas3, 2, 4, 1 and 5 with respect to the I picture as shown in FIG. 23. Thearrangement may have a structure shown in FIG. 28. In FIG. 28, when thedata of the I picture is recorded at the front portion of the dataarrangement of one GOP portion, the area number at the front of each ofthe GOPs is scrolled. In other words, as shown in FIG. 28, when the Ipicture data is recorded in the order of I(5), I(1), I(2), I(3), andI(4) in the nth GOP, the I picture data is recorded in the order ofI(1), I(2), I(3), I(4) and I(5) in the n+1th GOP. Further, I(2) comesfirst in the n+2th GOP. When the GOP number becomes n+3 and n+4and - - - , the front area is sequentially scrolled and recorded in theorder of I(3), I(4), I(5), I(1) and - - - .

Further, at the front of the GOP, the address where data in each Ipicture is stored and information for recognizing the kind of the frontarea are written as header information. As header information, the areanumber recorded at the front and the number of bytes indicating dataamount occupied on the data format of each area as shown in FIG. 27.Consequently, at the time of the playback, the data order of the Ipicture area and the end position of the each area on the recordingmedium can be recognized as relative addresses with respect to the frontof the GOP, with the front area number recorded in the headerinformation and the number of bytes occupied by each area on therecording medium. Consequently, at the time of the special playback, theoptical head jumps to the front address of the GOP in the unit of acertain period of time, so that the I picture data can be read for eacharea from the front of the GOP in accordance with the headerinformation.

In this case, the position where the I picture area divided into fiveareas is recorded is scrolled in the unit of GOP so that the area whichcannot be decoded is rot concentrated on the fixed position on thescreen even when only part of the area of the I picture can be decodedat the time of the special playback.

At the time of the high speed playback, the optical head jumps to thefront of the GOP in the unit of certain time with respect to the datarecorded on the recording medium such as an optical disc or the like toread the data portion of the I picture in the unit of area in accordancewith the header information and is demodulated at the demodulator 21 andis inputted to the buffer memory 22. However, when the informationamount of the I picture is too large to read the whole I picture in acertain time, the optical head jumps to the front of the subsequent GOPafter reading to the last data in the area which is read halfways toinput only the data in the area that can be read into the buffer memory22. In this case, the format decoder 23 decodes only the area of the Ipicture that can be read, which is outputted as a high speed playbackpicture. Consequently, in the case where one GOP is set to 15 frames, a15 times speed special playback picture is obtained.

FIG. 29 shows a playback picture in the case where the I picture of oneGOP is played back in a high speed playback. In this case, the I pictureis to be recorded on the recording medium in an order as shown in FIG.28. Here in the case where the information amount of the I picture islarge, and the whole I picture cannot be read in time, the data of thepreceding screen is held as it is and is outputted so that a high speedplayback picture is synthesized. FIG. 29 shows a case in which n+1th GOParea 5 and n+3th GOP areas 1 and 2 cannot be read completely. In thiscase, the data of the preceding screen is held as it is.

As described above, the order of recording the I picture used for thespecial playback as shown in FIG. 28 is scrolled in the unit of GOP.Consequently, even in the case where only some areas of the I picturecan be decoded at the time of the special playback, the area that cannot be decoded is not concentrated on the fixed position on the screen.

Embodiment 6

Next, embodiment 6 of the present invention will be explained withrespect to figures. FIG. 30 is a view showing a data arrangementstructure of a digital video data according to embodiment 6. In thiscase, the I pictures and the P pictures are divided into five areas eachhaving 720 pixels×96 lines so that each area is blocked in the unit ofthe macroblock and is coded as shown in FIG. 22. Each P picture isdivided into five areas. The motion compensation prediction is performedand coded in such a manner that the retrieval scope of the referencepattern of the motion compensation prediction closes in the area. Here,the divided five areas are defined as areas 1, 2, 3, 4 and 5 from thetop. Further, with respect to the B picture, the motion compensationprediction is performed and coded without being divided into areas.

With the format encoder 13, the data of one GOP portion is used torearrange the video signal with the data arrangement shown in FIG. 30and is outputted to the modulator 14. Here, with respect to the Ipicture and the P picture, one screen is divided into five areas asshown in FIG. 22. The I picture, and the P1, P2, P3 and P4 pictures aredefined as I(1) through I(5) and Pi(1) through Pi(5) (i=1 through 4). InFIG. 30, the data of the I picture, the P1, P2, P3 and P4 pictures isconstituted to be recorded in the order of 3, 2, 4, 1 and 5 from thefront of the data string for one GOP portion, so that the area locatedat the central part of the screen is given a priority. Further, in FIG.30, the data amount of each area is recorded as header information atthe front of one GOP so that the address of the data in each I pictureand P picture area can be recognized.

At the time of the high speed playback, the optical head jumps to thefront of the GOP with respect to the data which is recorded in the unitof one GOP on the recording medium such as optical disc or the like withthe result that the data portion of the of the I picture and the Ppicture is read in the unit of area and is demodulated by thedemodulator 21 and is inputted to the buffer memory 22. However, whenthe information amount of the I picture and the P picture is too largeto read the whole I pictures and P pictures in a definite time, theareas read halfways are read to the last. Then the optical head jumps tothe front of the GOP in the unit of a certain time so that only the datathat can be read is inputted to the buffer memory 22. In this case, theformat decoder 23 decodes only the areas of the I picture and the Ppicture that can be read and then output the data as a high speedplayback picture. Consequently, in the case where the one GOP is set to15 frames, a triple speed special playback picture can be obtained.

Further, since the area located at the central part of the screen isgiven a priority to be arranged at the front of one GOP out of the Ipicture divided into five sections, at least a playback picture at thecentral part of the screen can be outputted even in the case where onlya part of either the I picture or the P picture can be decoded. Furtherthe pictures are recorded on the recording medium in the order of the Ipicture, the P1 picture, the P2 picture, the P3 picture and the P4picture. Consequently, it never happens that the reference data cannotbe played back at the prediction data decoding circuit 27 even when allthe data cannot be read.

FIG. 31 shows a play back picture in the case where a high speedplayback of the picture is performed by playing back only the I pictureand the P picture in one GOP. In this case, when the whole I picture andthe whole P pictures cannot be read from the recording medium in adefinite time because the information amount of the I picture and the Ppictures are large, the data of the preceding screen is held as it isand outputted to synthesize a high speed playback picture with respectto the area that cannot be read. FIG. 31 shows the case where the areas3, 4 and 5 of the P4 of the nth GOP cannot be read. In this case, thedata of the preceding screen is held as it is.

As described above, as shown in FIG. 30, the I picture and the Ppictures are played back to output a special playback picture at thetime of the special playback by collecting and arranging the I pictureand the P picture used at the time of special playback in the unit ofarea at the front of the one GOP. Further, in the case where the whole Ipicture and the whole P picture cannot be read because of time limit,the data of the preceding screen is interpolated to allow output of theplayback picture.

In the aforementioned embodiment 6, in the case where the whole Ipicture and the whole P picture cannot be read, the playback picture isinterpolated in units of areas. However, the interpolation may not beperformed in area units, but it may be performed in units of errorcorrection codes.

In this case, the demodulator 21 segments the data into packets ofseveral bytes with respect to the data arrangement shown in FIG. 30 sothat an error correction code is added to each of the packets. FIG. 32shows a case in which the data of five areas inputted to FIG. 32 in acontinuous manner is divided into packets of error correction blocks.FIG. 32A shows the data string before the packet division. FIG. 32Bshows the data after the packet division. In FIG. 32, the data isdivided into ith through jth packets in the area P1(3).

At the time of the high speed playback, the optical head jumps to thefront of the GOP in units of a definite time with respect to the datawhich is recorded in the unit of GOP on the recording medium such as anoptical disc or the like with the result that the data portion of the Ipicture is read in units of area in accordance with the headerinformation and is demodulated at the demodulator 21 and is inputted tothe buffer memory 22. However, in the case where the information amountof the I picture is so large that the whole I picture and the whole Ppictures cannot be read in a definite time, the optical head jumps tothe front of the next GOP even in the midst of reading the data in onearea portion. Further, the data that has been read is subjected to anerror correction processing, and the data that can be error corrected isinputted to the buffer memory 22. In this case, the format decoder 23recognizes the address of the I picture and the P pictures that can bedecoded halfways so that the data that can be read is decoded in theunit of macroblock and is outputted as a high speed playback picture. Inthis case, with respect to the macroblock that cannot be decoded, thedata of the preceding screen is held it is end and is outputted.

In the aforementioned embodiment 6, in the motion compensationprediction, the scope of retrieval is set to be closed in each area, butit is not always required to be closed.

Embodiment 7

Next, embodiment 7 of the present invention will be explained withrespect to FIG. 33. FIG. 33 is a view showing a method for a specialplayback according to embodiment 7. In embodiment 6, the specialplayback is performed in a playback method as shown in FIG. 31. However,the special playback may be performed so that the playback picture isoutputted as shown in FIG. 33. In this case, the format encoder 23synthesizes one screen by playing back areas one by one from continuousfive frames as shown in FIG. 33. In FIG. 33A, a playback picture of onescreen portion is synthesized from the I picture, the P1 through P4pictures. Further, in FIG. 33A, the P4 picture is played back in thearea 1, the P3 picture is played back in the area 2, the P2 picture isplayed back in the area 3, and the P1 picture is played back in the area4 and the I picture in the area 5. Further, in FIG. 33, the area 5 isnoted with the passage of time. The played back video data includes theI picture of the nth GOP, the P1, P2, P3 and P4, and the I picture ofthe n+1th GOP picture, and the P1 picture.

Further, in the case where the information amount of the I picture andthe P picture is so large that all the I picture and the P picturecannot be read in a definite time, the data of the preceding screen isheld as it is and is outputted to synthesize a high speed playbackpicture. FIG. 34 shows a playback picture in the case where the areas 1,4 and 5 of the n-th GOP cannot be read. In this case, as shown in FIG.30, with respect to the data string, the area located at the center onthe screen is given the priority to be recorded on the recording mediumwith the result that it never happens that the playback picture is hardto see because the central part of the screen in given the priority inthe playback. Further, even in the case where the data in two or moreareas can not be read, one screen is divided into five areas and theframe played back in each area is different, it is hard to see that thedata is lacking in the playback picture.

Embodiment 8

Next, embodiment 8 of the present invention will be explained withrespect to the figures. FIG. 35 is a view showing a digital video dataarrangement structure in embodiment 8. In embodiment 6, the dataarrangement is written in the order of the areas, 3, 2, 4, 1 and 5 asshown in FIG. 30, but the arrangement may have a structure as shown inFIG. 35.

In FIG. 35, when the data in the I picture and the P pictures arerecorded at the front of the data arrangement for one GOP portion, thearea number at the front is scrolled for each of the frames. In otherwords, as shown in FIG. 28, in the nth GOP, the I picture data isrecorded in the order of the P1(2), P1(3), P1(4), P1(5) and P1(1).Further, in the P2 picture, P2(3) comes to the front. In the P3 picture,and the P4 picture, the front areas are scrolled and recordedsequentially like P3(4) and P4(5).

Further, at the front of the GOP, the address where the data of the Ipicture and the P picture are stored, and information for identifyingthe kind of the area at the front of each frame are recorded as headerinformation. Here, as header information, the area number which isrecorded at the front of each area and the number of bytes indicatingthe data amount in each area which is divided into five parts arerecorded. Consequently, the optical device jumps to the front of the GOPin the unit of a certain time at the time of the special playback sothat the data can be read in the unit of area in accordance with theheader information.

In this case, since the position where the I picture and P picture areasdivided into five parts are scrolled in the units of frames, it neverhappens that the area which is not decoded is not concentrated on thefixed position on the screen even in the case where only a part of theareas of the I picture and the P picture can be decoded.

At the time of the high speed special playback, the data which isrecorded on the recording medium such as an optical disc or the like inunits of one GOP is read in units of area in accordance with headerinformation. Then, the data is demodulated by the demodulator 21 and isinputted to the buffer memory 22. However, when the information amountof the I picture and the P picture is so large that the whole I pictureand the whole P picture cannot be read in a definite time, the data isread to the last with respect to the area read halfways. Then, theoptical head jumps to the front of the GOP to input data only of thearea which can be inputted into the buffer memory 22. In this case, theformat encoder 23 decodes only the area of the I picture and the Ppicture, and is outputted as a high speed playback picture.

FIG. 36 shows a playback picture in the case where only the I pictureand the P picture in one GOP are played back for a high speed playback.In this case, when the data amount of the I picture and the P picture isso large that the whole I picture and P picture cannot be read in adefinite time, a high seed playback picture is synthesized by holdingand outputting the data of the preceding screen as it is. FIG. 36 showsa case where the areas 3, 4 and 5 of the P4 of the nth GOP cannot beread. In this case, the data of the preceding screen is held as it is.

As described above, since the order of recording the I picture used forthe special playback is scrolled in the unit of GOP a shown in FIG. 35,the area which cannot be decoded is not concentrated on the fixedposition on the screen even in the case where only a part of the areasof the I picture can be decoded at the time of the special playback.

Embodiment 9

Next, embodiment 9 of the present invention will be explained withrespect to FIG. 37. FIG. 37 is a block diagram on the recording sideshowing a digital video signal coding processing unit in a digital videorecord and playback device wherein the DCT block is divided into stagesin the low frequency area and the high frequency area so that only thelow frequency area is located at the front of the GOP. In FIG. 37,reference numeral 51 denotes a buffer memory, 52 a subtracter, 53 a DCTcircuit, 54 a quantizer, 55 a variable-length encoder, 56 an inversequantizer, 57 an inverse DCT circuit, 58 an adder, 59 a motioncompensation predicting circuit, 60 a counter for counting the number ofevents and a code amount, 61 a format encoder, and 65 an input terminal.

Next, an operation of the device will be explained. The video data to beinputted is an interlace picture which has an effective screen size ofhorizontal 704 pixels and vertical 480 pixels. Here, the operation ofthe subtracter 52, the DCT circuit 53, the quantizer 54, thevariable-length encoder 55, the inverse quantizer 56, the inverse DCTcircuit 57, the adder 58 and the motion compensation predicting circuit59 are the same as the counterparts shown in conventional embodiments.Thus, an explanation thereof will be omitted.

An operation of the variable-length encoder 55 will be explained withrespect to FIG. 38. FIG. 38 shows a data arrangement of DCT coefficientsinside of a DCT block. In FIG. 38, a low frequency component is locatedat the upper left portion and the data of the DCT coefficient of a highfrequency component is located at the lower right portion. The data ofthe low frequency coefficient up to a specific position (the end of theevents) (for example, the hatching part in FIG. 38) out of the data ofthe DCT coefficient arranged in the DCT block is coded into avariable-length code as a variable-length area and is outputted to theformat encoder 61. Then, the variable-length coding is applied to thedata of the DCT coefficient after the data of the DCT coefficient at theaforementioned position. In other words, the data in the space frequencyarea is coded through partitioning.

A boundary between the low frequency area and the high frequency area isreferred to as a breaking point. The breaking point is set to assume apredetermined code amount in the low-frequency area which the opticalhead can assess at the time of the special playback. The variable-lengthencoder 55 divides the DCT coefficient into the low-frequency area andthe high-frequency area in accordance with the breaking point to beoutputted to the format encoder 61.

The determination of the coding area is performed at the boundary of theevent. It goes without saying that the determination can be made byother methods. For example, the determination of the coding area can bemade at the boundary of the fixed number of events. The data may bedivided with the quantizer 54 with the quantization data subjected to arough quantization with the quantizer 54 and a differential valuebetween a fine quantization and a rough quantization. Further, the datamay be divided with coding of a picture whose space resolution isthinned to a half level with the buffer memory and a coding of adifferential picture between a picture whose resolution is brought backfrom the half level and a picture with an original resolution. In otherwords, the data division is not limited to the division of the frequencyarea. It goes without saying that the high efficiency coded data of thepicture may be divided by the quantization and the division of the spaceresolution.

At this time, more important data as a picture is a low frequency areadata in the division by the frequency. When the division is the divisionby quantization, the data is subjected to a rough quantization forcoding. When the data is divided with the space resolution, the thinnedpicture is coded. By decoding only these important data, a decodedpicture can be obtained which can be easily perceived by man. In thismanner, one high efficiency coded data is divided into more fundamentaland important data and other data (this process is referred to ashierarchization). An error correction code is added and modulation isperformed to be recorded on a disc.

In this manner, since only the low-frequency component of the I pictureand the P picture are divided, reading and playing back only theselow-frequency components at the time of the special playback largelyreduces the amount of data which is read at the time of the specialplayback. As a consequence, time for reading data from the mediumbecomes shorter so that a high speed playback of a smooth movement canbe realized at the time of skip search. Further, when only the I pictureand the P picture are arranged in a consecutive manner, the data of thelow-frequency component of the I picture and the P picture can be easilyread from the disc to be decoded. In this case, more efficient datastructure can be made by extracting and arranging only the low-frequencycomponent than by arranging the whole area of the I picture and the Ppicture at the front of the GOP.

Next, an operation of the format encoder 61 will be explained. FIG. 39is a flowchart showing a movement of a format encoder. In the beginning,when the encoding operation is started, it is judged that the encodingmode is in a hierarchical mode or not. When the mode is not thehierarchical mode, information is inserted into a system stream whichinformation is representative of the fact that the mode is anonhierarchical mode to follow the conventional stream structure. In thecase of the hierarchical mode, the setting of the sequence header isconfirmed. Specifically, the data of the sequence scalable extension isconfirmed. When the data is written correctly, the front of the pictureis recognized so that the I picture and four P pictures are separatedinto the data of the low-frequency component and the data of the higharea component to detect respective data lengths.

In the meantime, the length of the data of the B picture is detected foreach of the pictures. Further, a packet is prepared where only addressinformation is recorded in the case where the data of the low-frequencycomponent of the I picture and the P pictures area is arranged to followthe front of the GOP. In this packet, address information for thelow-frequency component of the I picture and the P picture, thehigh-frequency component of the I picture of the four P pictures and tenB pictures are contained so that the data length for the respective datais recorded.

Consequently, the front position of respective data stream is obtainedas a relative address with respect to the front of the GOP header fromthis data length. The packet containing this address information and thelow-frequency component of the I picture and four P pictures as well asthe remaining data are sequentially arranged to be formatted.

Out of them, the confirmation of the scalable mode on the scalableextension of the aforementioned sequence header refers to theconfirmation of the scalable mode setting which is determined in thesyntax of the MPEG2 of FIG. 40 and the confirmation of the descriptionof the priority break point on the slice header. The priority breakpoint is located at a predetermined number of events of FIG. 40(corresponding to the aforementioned breaking point) and refers to thedata representative of the boundary between the divided low-frequencycomponent and the high-frequency component.

When a scramble mode assumes “00”, it is shown that the followingbitstream is a bitstream of a data partitioning. It is also shown thatthe bitstream which is divided into the low-frequency component and thehigh-frequency component continues. When the B picture consists of thelow-frequency component so that no high-frequency component isgenerated, the B picture is not divided.

One example of the bitstream which is generated in this manner is shownin FIG. 41. FIG. 41A shows a bitstream which is not hierarchized. Whenthe bitstream is hierarchized with a circuit shown in FIG. 37, thebitstream is divided and hierarchized as shown in FIG. 41B. When thisdata is arranged in an array in consideration of this special playback,the low-frequency component of the I picture and the P picture isarranged at the front of the GOP as shown in FIG. 41C.

FIG. 41D shows a data arrangement in the case where address informationis contained in the private packet as shown in a flowchart in FIG. 39.In this case, the address information may be represented with a relativeaddress with respect to the front of the GOP header as described above.However, the address information may be represented in such a mannerthat which byte of which packet is the front of each picture. It goeswithout saying that the address information may be represented with asector address on the disc as well.

FIG. 42 shows an example in which address information is contained in aprivate packet. When a packetized elementary stream (which is referredto as PES) packet is used as a private packet, the stream ID isspecified in BF (hexadecimal number representation). After describingthe packet length, the byte MSB is set to 1 and the subsequent bit isset to 0 so that the code does not become the same as all the startcodes (start code of packet and the start code of the bitstream). Thenthe hierarchical mode, the kind of hierarchization, the kind of pictureto be used at the time of the special playback, and the number of thestart addresses or the like are described with the remaining six bits.

After that, the 21 bit long address information is described so that theGOP data amount can be represented up to a maximum length of 2 Mbytes.However, 100 (represented in binary representation) is inserted into thefirst 3 bits out of 21 bits of data so that the data does not become thesame as the front 24 bits 000001 (hexadecimal representation) of thestart code as described above. Here, the start address includes a startaddress of the low-frequency component of the I picture, a start addressof the high-frequency component of four P pictures and a start addressof the high-frequency component of the I picture, the high-frequencycomponent of four P pictures, and a start address of ten B pictures.Further, a sector address on a disc where the data of the preceding andsucceeding GOP is recorded is added to jump an optical head at the timeof the special playback.

When the 1 bit parity is added to the 21 bit addresses, the reliabilityof the data is heightened. In this case, 10 (binary representation) maybe added to the front with respect to 21 bits+1 bit. Further, inconsideration of the high-speed times of the special playback, thevariation in the high-speed times of the special playback is widenedwhen the sector address of the several front and rear GOPs is added aswell as the address of the preceding and succeeding GOP. Further, it isshown that address information is described in the private two packetsof the PES packet. It goes without saying that the sector address may bewritten on other user areas or the like such as private descripter of aprogram stream map or the like.

The playback side of embodiment 9 will be explained with respect to FIG.43 and FIG. 44. FIG. 43 is a block diagram of a digital video signaldecoding processing part. In FIG. 43, reference numeral 71 denotes aprogram stream header detector, 72 a PES packet header detector, 73 avideo bitstream generator, 74 a data rearranger, 75 an address memory,76 a mode switcher, 77 a variable-length decoder, 78 a switch, 79 aninverse quantizer, 80 an inverse DCT circuit, 81 an adder, 82 aprediction data decoding circuit, 83 a frame memory and 84 a decodabledeterminer. FIG. 44 is a view showing an operation concept of FIG. 43.

Next, an operation of FIG. 43 will be explained with respect to FIG. 45.FIG. 45 is a flowchart showing an operation of a format decoder at thetime of the playback. The bitstream outputted from the ECC is detectedthe header of a program stream to be divided into each PES packet.Further, the PES packet header is detected to differentiate a privatepacket including address information and a video packet.

In the case of a private packet, the address information contained inthe packet is extracted and stored. In the meantime, in the case of thevideo packet, the bitstream of the video data is extracted. Here, in thecase of the normal playback, the data of the low-frequency component andthe high-frequency component is extracted from the bitstream stream ofthe video data with respect to the I picture and the P picture so thatthe data is rearranged and a playback picture is outputted. In themeantime, at the time of the special playback, only the low-frequencycomponent of the video data is extracted and played back. Here, afterthe low-frequency component is played back, the optical head is allowedto jump to the front of the subsequent GOP.

In this case, when these addresses are described in the video stream,the address information is extracted and stored after being convertedinto the bitstream. Consequently, in the case where the addressinformation is described in the private descripter of the program streammap, the address information is extracted and stored at a level of thedetection of the program stream header. It goes without saying that theaddress information may be either a relative address or an absoluteaddress.

In actuality, a mode signal of such as skip search and a normalcontinuous playback or the like is inputted to the mode switcher 76. Inthe meantime, a playback signal from a disc or the like is amplified byan amplifier so that the signal is played back with a clock which hasbeen subjected to a phase synchronization and outputted from a PLL orthe like. Next, a differentiation operation is performed for digitaldemodulation. Then, after an error correction processing is performed,the program stream header detector 71 obtains data information thatfollows the header.

Further, the PES packet header detector 72 detects, for example, addressinformation for each picture described in the private 2 packet of thePES packet and address information of the data for the special playbackand the information is stored in the address memory 75. Here, the PESpacket for the audio, the PES packet for such as characters or the likeand the PES packet for the video are classified so that only the packetfor the video is outputted to the video bitstream generator 73.

Here, the video bitstream generator 73 erases added information from thePES packet and constructs a bitstream. Specifically, the data such aseach kind of control code and the time stamp is eliminated. After this,in accordance with the address information obtained from the addressmemory 75, with the output of the mode switcher 76, the bitstream isrearranged at the time of the normal playback by the data rearranger 74.

The output (control signal) of the mode switcher 76 is supplied to thedata rearranger 74 and the decodable determiner 84. The data rearranger74 either reconstructs the data before the division from thelow-frequency component and the high-frequency component divided andhierarchized by obtaining the control signal. Otherwise, only thelow-frequency component is outputted to the variable-length decoder 77.In other words, each of the low-frequency components is synthesized withthe high-frequency component at the time of the normal playback so thatthe device is operated in such a manner that the data is rearranged inan order of the original picture. At the time of the special playback,either the low-frequency component only of the I picture or thelow-frequency component of the I picture and the P picture is outputteddepending on the high-speed times.

At the time of the special playback that allows the passage only of thelow-frequency component, the time stamp is not used. In contrast, thevariable-length decoder 77 extracts the boundary of the events in thelow-frequency component area designated by the priority break points ofthe slice header together with the decodable determiner 84 so that thedata is decoded up to the boundary and is outputted to the switch 78.This switch 78 is connected so that zero is not inserted at the time ofthe normal playback. In the meantime, at the time of the specialplayback, the switch 78 is controlled with the decodable determiner 84so that zero is inserted into the high-frequency component area afterthe priority break point at the time of the special playback.

The aforementioned operation will be explained with respect to FIG. 44.Referring to FIG. 44, when the partitioning breaking point is E1 throughE3, E1 through E3 is stored in the stream of the low-frequencycomponent. E4 through EOB are stored in the stream of the high-frequencycomponent. In the stream of the low-frequency component, thelow-frequency component data in the subsequent DCT block following E3 isstored.

Here, at the time of the normal playback, the data rearranger 74extracts the data E1 through E3 from the low-frequency component streamand the data E4 through EOB from the high-frequency component stream.Further, the data rearranger 74 extracts the data respectively toreconstruct the DCT data in sequency. In contrast, at the time of thespecial playback, the data rearranger 74 extracts the data E1 through E3followed by variable-length decoding by the variable-length decoder 77,the decodable determiner 84 detects the priority break point so thatzero is inserted into a portion provided with a hatching shown in FIG.44 to constitute a DCT block by using only a low-frequency component.

The data which is converted into the DCT block is decoded in accordancewith the motion vector. Here, an explanation of the decoding by themotion vector will be omitted because the decoding is the same as theconventional example. However, the reference used in the decoding of theP picture at the time of the special playback is decoded by using the Ipicture or the P picture which is decoded only with the low-frequencycomponent.

The data which is decoded in the unit of block is inputted to the framememory 83. Here, the frame memory 83 restores the picture in theoriginal order of the structure of the GOP, and outputs through theconversion from the block scan to the raster scan. Incidentally, theframe memory 83 can be commonly used with the memory incorporated in theprediction data decoding circuit 82.

The coding area is defined at the boundary of the events, but it goeswithout saying that the definition of the boundary can be made by othermethods. In other words, the high efficiency coded data of the picturemay be divided either with the quantization or the division of the spaceresolution in addition to the division of the frequency area.

At this time, data more important as a picture is data of thelow-frequency area in the case of the frequency division. In the case ofthe division of the quantization, the data refers to data coded by arough quantization. In the case of the data divided with the spaceresolution, the data refers to the data obtained by coding the thinnedpicture. In this case, in the playback picture decoded by using onlythese data items, the area which can be easily perceived by men isdefined as important data. In other words, one high efficiency codeddata is divided into basic and important data and data which is not soimportant (this process is referred to as hierarchization) so that onlybasic and important data can be played back at the time of the specialplayback when the data is played back from the disc.

Embodiment 9 describes a case in which the recording side corresponds tothe playback side. It is also considered that in the case where therecord and the playback is combined in a set such as a hard disc or thelike, only the playback side is considered on the presupposition thatthe data is recorded in accordance with the concept of theconventionally available compact disc or the like.

Embodiment 10

Next, embodiment 10 of the present invention will be explained. FIG. 46is a block diagram showing a record system of the digital video signalrecord and playback device according to embodiment 10 of the presentinvention. Like numerals in FIG. 46 denote like parts or correspondingparts in FIG. 37. Reference numeral 65 denotes an input terminal, 51 abuffer memory, 52 a subtracter, 53 a DCT circuit, 54 a quantizer, 56 aninverse quantizer, 57 an inverse DCT circuit, 58 an adder, 59 a motioncompensation predicting circuit, 55 a variable-length encoder, 62 anarea rearranger, and 61 a format encoder.

FIG. 47 is a block circuit diagram showing a playback system of adigital video signal record and playback device according to embodiment10 of the present invention. Like numerals in FIG. 47 denotes like partsor corresponding parts in FIG. 43. Reference numeral 71 denotes aprogram stream header detector, 72 a PES packet detector, 73 a videobitstream generator, 85 an area rearranger, 75 an address memory, 76 amode switcher, 77 a variable-length decoder, 79 an inverse quantizer, 80an inverse DCT circuit, 81 an adder, 82 a prediction data decodingcircuit, and 83 a frame memory.

Next, an operation of embodiment 10 will be explained. The digital videosignal is inputted in the unit of line from the input terminal 65, andis supplied to the buffer memory 51. Here, an operation from the buffermemory 51 to the variable-length encoder 55 is the same as theaforementioned example, and an explanation thereof will be omitted.

The area rearranger 62 rearranges data with respect to the I picture ina bitstream of video data outputted in the unit of GOP from thevariable-length encoder 55, so that an area located at the central partof the screen is arranged at the front of the bitstream. Here, the Ipicture is divided into three areas as shown in FIG. 48. The data of theI picture corresponding to the areas 1 through 3 are defined as I(1),I(2), and I(3). However, each area shown in FIG. 48 is a collection of aplurality of MPEG slice layers. In FIG. 48, the area 1 and 3 consists ofsix slices and the area 2 consists of 18 slices.

In actuality, the area rearranger 62 detects the slice header of the Ipicture on the bitstream and classifies each slice into three areasshown in FIG. 48 thereby forming a bitstream for each of the areas forrearranging the bitstreams arranged for each of the areas. In otherwords, as shown in FIG. 49, the bitstreams are rearranged in the unit ofarea so that the bitstream is arranged in the order of I(2), I(3) andI(1) at the front of the GOP. Further, the rearranged bitstreams areoutputted to the format encoder 61 in the unit of GOP.

Next, an operation of the format encoder 61 will be explained inaccordance with FIG. 50. FIG. 50 is a flowchart showing an algorithm forformatting the video data into the PES packet in the unit of GOP. In thecase of the screen central part priority mode, the picture header of thebitstreams to be inputted is detected and the picture information isdetected. Here, in the case of the I picture, the central parts of thescreen I(2), I(3) and I(1) shown in FIG. 49 are extracted and respectivedata lengths are detected so that the data length of each area thusdetected is converted into a binary number of 24 bit width therebypreparing an address information. On the other hand, the data lengthsare detected in the unit of picture with respect to the P picture andthe B picture so that the data lengths are converted into a binarynumber of 24 bit (3 bytes) width thereby preparing address information.

Further, the formatting unit collects the input address information andthe bitstreams of the video data into two kinds of the PES packets. Inother words, the PES packet having only the address information and thePES packet having only the audio are constituted.

Consequently, when one GOP consists of 15 frames as shown in FIG. 6,there are 17 kinds of pictures as the address information, such as threekinds of I pictures, four kinds of P pictures, 10 kinds of B pictures.Further, as address information at the time of the special playback,there are two kinds of address information of the preceding andsucceeding GOP on the disc (absolute addresses on the disc) These itemsof the address information are collected in one packet and are formattedas the PES packet. In actuality, these items of address information arecollected in one packet and are formatted as a private 2 packet of thePES packet shown in FIG. 51. In FIG. 51, the absolute address on thepreceding and succeeding GOP on the disc is arranged at the front of thepacket data. Then, the address information of each picture is arrangedin order. However, since 3 bytes (24 bits) long information is assignedto each address information, the packet has a length of 57 bytes.

In the meantime, with respect to one GOP portion of bitstreams otherthan the address data, the bitstreams are formatted into PES packets(video packets) by dividing the bitstreams into a plurality of packetsand adding header information such as synchronous signals or the like.

In addition, the format encoder 61 divides the bitstreams of theinputted audio data into PES packets to constitute an MPEG2-PS systemstream together with the PES packets of the video data. In actually, asshown in FIG. 52, the bitstreams of one GOP portion of the video dataand the bitstreams of the audio data are divided and arranged into aplurality of packets in one pack. In this case, a packet representativeof the aforementioned address information is arranged at the frontpacket of the system stream as shown in FIG. 52. Subsequently, thedevice is constituted in such a manner that the packet containing thebitstream at the central part of the screen of the I picture isarranged.

Next, an operation at the time of the playback will be explained withrespect to FIG. 47. In FIG. 47, since an operation of the program streamheader detector 71, the PES packet header detector 72, the videobitstream generator 73 and the mode switcher 76 is the same asconventional examples, an explanation thereof will be omitted.

In the decoded video bitstreams, the data at the central part of thescreen of the I picture is located at the front of the bitstream.Consequently, the area rearranger 85 rearranges the I picture data inthe order of I(1), I(2) and I(3) for each area in accordance with thedata length of bitstreams of I(2), I(3) and I(1) which is outputted fromthe address memory 75. The rearranged bitstreams are inputted to thevariable-length decoder 77 to be decoded into the block data, the motionvector or the like. Here, since an operation which follows thevariable-length decoding at the time of the normal playback is the sameas conventional examples, an explanation thereof will be omitted.

In a high speed playback, since one GOP portion of data is assigned toone pack of a system stream as described above, there is considered amethod by which an optical head jumps to the front address of each GOPwhen reading data from a disc to read only the data of the I picturewhich is arranged at the front of the system stream so that the opticalhead jumps to the front of the subsequent GOP. In such a case, the PESpacket is detected which has a record of address information arranged atthe front of th system stream to control the disc drive by decoding theaddress on the disc of the subsequent GOP and the address information ofthe I picture.

In the case shown in FIG. 6, when all the I pictures in each GOP can beread within one frame, a 15 times high-speed playback can be realized.When the I pictures in each GOP are read within 2 frames, a 7.5 timeshigh-speed playback can be realized. In this manner, when the higherspeed of playback can be realized, time for reading data from the discbecomes shorter.

Further, in the case where data is read from the recording medium suchas an optical disc or the like, even if the front address is known,there arises disc rotation waiting time at the time when the opticalhead jumps to a location of the disc where the data is actuallyrecorded. Further, when the video signal is coded with a variable rate,the amount of information of the I picture is not definite and timerequired for reading the I picture also varies. Consequently, when thespeed in the high-speed playback becomes higher, time for reading dataon the disc becomes shorter. Further, since the waiting time for thedisc rotation is not definite, it becomes impossible to read stably thewhole data of the I picture.

Consequently, in embodiment 10, the optical head jumps to the front ofthe GOP in the unit of a definite time with respect to the data recordedin the unit of GOP on the recording medium such as an optical disc orthe like at the time of the high-speed playback. Thus the data part ofthe I picture is read from the disc. In this case, even if the wholedata of the I picture cannot be read, the optical head jumps to thefront of the subsequent GOP. In other words, the optical head jumps tothe front address of each GOP in the unit of a certain time to read dataas much as possible from the front of the system stream and then jumpsto the front of the subsequent GOP.

In this case, the PES packet including the address on the disc or thelike of the subsequent GOP and the PES packet including the data at thecentral part of the I picture are arranged at the front part of thesystem stream. Consequently, even in the case where the whole data ofthe I picture can not be read at the time of the special playback, atleast the address on the subsequent GOP disc and the data at the centralpart of the I picture can be decoded, the address and the data beingrequired for controlling the disc drive.

In the case where only the central part of the screen can be decoded atthe time of the special playback, only the data which can be decoded bythe area rearranger 85 is outputted to the variable-length decoder 77 sothat the variable-length decoded video data is inputted to the framememory 83 through the inverse quantization and inverse DCT. In themeantime, the area rearranger 85 inputs the area information whichcannot be decoded into the frame memory 83. With respect to the areawhich cannot be decoded, the data outputted in the preceding frame isheld as it is and is outputted.

FIG. 53 shows one example of playback picture in the case where ahigh-speed playback is performed by playing back only the I picturesfrom the nth GOP to the n+4th GOP. FIG. 53A shows a case in which thewhole I picture can be decoded. FIG. 53B shows a case in which areas 2and 3 can be decoded. In the area 1 which cannot be decoded, the valuein the preceding frame is held as it is and outputted. In addition, FIG.53C shows a case in which only the area 2 can be decoded. In the areas 1and 3, the value in the preceding frame is held as it is.

Here, in the general video signal record and playback device, a formatis adopted in which the I picture is recorded in the unit of frame atthe time of recording. In contrast, in FIG. 52, the area located at thecentral part of the screen out of the I picture data which is dividedinto three parts is arranged at the front of one GOP by giving apriority to the area. Consequently, even in the case where the area ofonly part of the I picture can be read from the disc in a definite timeat the time of the special playback, the playback picture at least atthe central part of the screen can be outputted.

As described above, in embodiment 10, as shown in FIG. 52, with respectto the I picture for use in the special playback, data of the arealocated at the center of the screen is arranged at the front of one GOPso that the area is given a priority to be recorded on the recordingmedium so that the area 2 located at the central part of the screen isgiven a priority to be played back even when the speed in high-speedplayback is high so that the content of the high speed playback pictureis easy to see. Further, the special playback is performed in which theoptical head jumps to the front of the GOP in the unit of a definitetime with the result that an output screen can be renewed at apredetermined high-speed.

Incidentally, the aforementioned embodiment may be constituted so thatdata of an area that can be decoded at the time of the special playbackis all outputted, and for the area whose data cannot be decoded, thedata of the preceding frame is held as it is. However only the centralpart of the screen may be played back at the time of the specialplayback.

In this case, the area rearranger 85 decodes the data only of the areaof the I picture which is read from the disc. With respect to the areas1 and 3 whose data is not decoded, for example, it is masked by a graydata to output a high speed playback picture at the frame memory 83.

FIG. 54 shows a playback picture in the case where only the area 2 ofthe I picture from the nth GOP to the n+4th GOP is played back for thehigh speed playback. In FIG. 54, the areas 1 and 3 on both ends of thescreen in FIG. 54 are masked by gray data. Further, even in the casewhere the information amount of the I picture is small, the waiting timefor the disc rotation is short, and sufficient time is available forreading the data of the areas 1 and 3, the data of the areas 1 and 3 arenot decoded.

This is because the high speed playback picture becomes unnatural if thedata of the areas 1 and 3 are outputted on the screen only when they canbe read, and the areas 1 and 3 are not renewed in a certain interval.Consequently, when only the central part of the screen of the I pictureis played back at the time of the special playback, the area to berenewed becomes constant so that the playback picture becomes free fromunnaturalness.

Further, in the aforementioned embodiment, only the area of the centralpart of the I picture which can be decoded at the time of the specialplayback is displayed to mask both ends of the screen. However, thecentral part of the screen may be extended to a size of one screen andoutputted.

In this case, in the frame memory 83, the data of the decoded area 2 isextended to a size of one screen as shown in FIG. 55. However, in thecase of FIG. 55, the central part (FIG. 55A) of the area 2 surrounded bya dot line is extended to double the size by linear interpolation in thehorizontal and vertical directions. In other words, in the case of FIG.55, the part surrounded by a dot line has a size of horizontal 360pixels×vertical 240 lines. This dot part is extended by linearinterpolation to a size of one screen consisting of horizontal 720pixels×vertical 480 lines.

Accordingly, when only data of the area of the central part of thescreen is decoded at the time of the special playback to extend thecentral part to a size of one screen. The area whose data is outputtedbecome small. In this way, however, the masked part at the both ends ofthe screen which is conspicuous when only the central part of the screenis outputted can be eliminated.

In the aforementioned embodiment, only the central part of the screen ofthe I picture is given priority to be arranged on the bitstream.However, another constitution is also possible in which the central partof the screen of the P picture as well as that of I picture are givenpriority. In this case, the data of the central part of the screen ofthe P picture is arranged after the bitstream of the I picture.

In the aforementioned embodiment, the picture data is rearranged in theunit of area after the data is converted into the bitstreams. However,the picture data may not necessarily be rearranged after the data isconverted into the bitstreams. The picture data may be rearranged beforethe data is converted into the bitstreams.

FIG. 56 shows a flowchart of the playback side of embodiment 10. Theprocedure of the flowchart is already described above and is omittedhere.

Embodiment 10 is described by corresponding the recording side with theplayback sides There is also considered a case in which the record andplayback constitute a pair like a hard disc. There is also considered acase where the playback side on a presupposition that data is recordedin accordance with the supposition like a current compact disc. Further,it goes without saying that the data rearrangement of the screen in theunit of area can be realized in the prediction data decoding circuit 82and the frame memory 83 by using the data of the lower 8-bit long slicevertical position of the slice start code in the slice head.

Embodiment 11

Next, embodiment 11 of the present invention will be explained. FIG. 57shows a digital video signal coding processing unit in a digital videosignal record and playback device wherein the DCT block is hierarchizedinto a low-frequency are and a high-frequency area. Further, FIG. 57 isa block diagram on the recording side in which the screen is dividedinto a plurality of areas so that the central part of the screen of thelow-frequency area is given a priority to be arranged at the front ofthe GOP. In FIG. 57, reference numeral 62 denotes an area rearranger.Like parts and corresponding parts in FIG. 57 are denoted by likenumerals and an explanation thereof will be omitted.

Next, an operation of the device will be explained. This video data tobe inputted includes an effective screen size with horizontal 704pixels×vertical 480 pixels. The motion compensation and the DCT are usedto apply high efficiency coding to the picture data. Here, the operationup to the data division and hierarchization is the same as embodiment 9,and an explanation thereof will be omitted.

Embodiment 11 is the same as embodiment 9 in that the data may bedivided with the quantification and space resolution as well as with thefrequency area with respect to the division hierarchization. Inembodiment 11, important data further divided and hierarchized with thedata rearranger 62 is divided for each area of the screen as shown inembodiment 10 so that the central part of the screen is given a priorityto be arranged at the front of the GOP. In other words, the data isdivided into important data and data which is not important so that thedata is recorded on the disc in the priority order which ispreliminarily determined in an area.

In this manner, the low-frequency components of the I picture and the Ppictures are divided so that the central part of the screen is given apriority in the arrangement. When only the central part of the screen ofthese low-frequency components are read and played back at the time ofthe special playback, the data amount which is read at the time ofspecial playback will be largely decreased. Consequently, an allowancecan be made for the reading speed from the recording medium so that anextremely fast skip search can be actualized at a speed of more than tentimes speed or tens of times speed.

Here, the central part of the screen of the low-frequency of the screenis arranged at the front of the GOP, and the data of the P pictures arearranged following the data of the peripheral part of the screen in thelow-frequency area of the I picture with the result that a high-speedplayback can be realized at more than ten times speed or tens of timesof speed by playing back only the central part of the screen in thelow-frequency of the I picture. Further, the central part of the screenfor the low-frequency component of the I picture and the P picture forthe special playback has a small amount of data so that the data in thecentral part of the screen can be easily read and decoded from the disc.Thus a high-speed playback can be realized at several times speed. Inother words, since the data amount at the central part of the screen forthe low-frequency component of the I picture and the P picture has asmaller amount of data than that of entire low-frequency component, thespecial playback can be realized at a speed faster than embodiment 9.

Next, an operation of the area rearranger 62 and the format encoder 61will be explained. FIG. 58 is a flowchart thereof. In the beginning,when the encoding is started, the slice header of the I picture of thelow-frequency component partition is detected so that each slice isclassified into three areas shown in FIG. 48. Then bitstreams for eacharea are prepared for rearranging the bitstreams collected for eacharea. In other words, the data is rearranged for each area so that thebitstreams are arranged in the order of a low-frequency area I(2), alow-frequency area I(3), and a low-frequency area I(3) at the front ofthe GOP with respect to the low-frequency area I picture like FIG. 49.

Then, in the case of the screen central part priority mode, the pictureheader of the bitstreams to be inputted is detected to detect thepicture information. Here. in the case of the low-frequency area Ipicture, the central part I(2) of the low-frequency area screen, thelow-frequency area I(3) and the low-frequency area I(1) are extracted todetect the data length thereby preparing address information from thedata length of each area. In the meantime, in the case of the P pictureand the B picture the data length is detected in the unit of picturethereby preparing address information. In modes other than the screencentral part priority mode, the operation follows embodiment 9.

Next, the hierarchical mode is judged. In modes other than thehierarchical mode, information is inserted into the system streams whichrepresents that the mode is non-hierarchical thereby following thestructure of the conventional streams. In the case of the hierarchicalmode, the setting of the sequence header is confirmed. Specifically, thedata of the sequence scalable extension is confirmed. In the case wherethe data is correctly described, the front of the picture is recognizedwith the picture header so that the low-frequency area data in the Ipicture and the P picture rearranged in the screen area is extracted andthe data length is detected. In the meantime, the data length of the Bpicture is detected for each picture.

Further, a packet is prepared wherein only address information isrecorded in the case where the screen central part of the low-frequencyarea of the I picture and the P pictures is collected at the front ofthe GOP. This packet includes the screen central part of thelow-frequency area part of the I picture and the P picture, theperipheral part of the screen, the high-frequency area part of the Ipicture and P pictures, and address information of the B picture so thatthe data length of respective data is recorded. Consequently, the frontposition of respective data streams are obtained as relative addresswith respect to the front of the GOP header.

FIG. 59 shows bitstreams prepared in this manner. As shown in FIG. 59C,the low-frequency areas of the I picture and the P pictures rearrangedin the unit of area are arranged at the front of the GOP. Consequently,FIG. 59D shows a case in which the rearranged data of low-frequencyareas are packetted so that the address information is arranged in theprivate 2 packet as shown in the flowchart of FIG. 58. In this case, theaddress information may be represented with a relative address withrespect to the front of the GOP head as described above. Otherwise, theaddress information may be represented in such a manner that which byteof which packet falls on the front of each picture. It goes withoutsaying that the address information may be represented with a sectoraddress on the disc in addition to it.

FIG. 60 shows an example in the case where the address information iscontained in the private 2 packet . In the case where the PES packet isadopted as the private 2 packet , the stream ID is set, so that thehierarchical mode, the kind of hierarchization, the kind of picture usedat the time of the special playback and the number of start addressesare described. Here, the start address refers to the start address ofthe screen central part of the low-frequency area of the I picture, thestart address of screen peripheral part of the low-frequency area of theI picture, the start address of the remaining B picture.

Further, a sector address of the preceding and succeeding GOP on thedisc is added for allowing the optical head to jump at the time of thespecial playback. In this case, when the sector address of the severalfront and rear GOP is further added in addition to the address of thepreceding and succeeding GOP in consideration of the high-speed times atthe time of the special playback, the variation of high-speed times ofthe special playback will be widened. Further, it is shown that theaddress information is described in the private 2 packet of the PESpacket. It goes without saying that the address information may bedescribed in the private descripter of the program stream map, otheruser areas or the like.

The playback side of the device in embodiment 11 will be described inaccordance with FIG. 61. FIG. 61 is a block diagram of the digital videosignal decoding unit. Like parts or corresponding parts in the figureare denoted by like numerals, and an explanation thereof will beomitted.

Next, an operation of FIG. 61 will be explained in accordance with FIG.62. FIG. 62 is a flowchart showing an operation of the format decoder atthe time of the playback. The bitstream outputted from the ECC isdetected the header of the program stream and is separated for each ofthe PES packet. Further, the bitstream is detected the header of the PESpacket to differentiate the private packet containing the addressinformation and the video packet.

In the case of the private packet, the address information contained inthe packet is extracted and stored. In the meantime, in the case of thevideo packet, the bitstreams of the video packet is extracted. Further,in the case of the private packet and normal playback, or in the case ofthe video packet, the data of the low-frequency component and thehigh-frequency component is extracted from the bitstreams of the videodata of the I picture and the P pictures so that the data is rearrangedfor outputting a playback picture.

In the meantime, in the case of the private packet and the specialplayback, it is judged in the beginning whether or not time is availablefor playing back the whole low-frequency I picture. In the case wheretime is available for the playback, it is further judged whether time isavailable for playing back the low-frequency P pictures. Theaforementioned two or one judgements are made. Thus, in the case wheretime is available for playing back the low-frequency I picture and Ppictures, the I picture and the P pictures are played back. In the casewhere time is available for playing back the whole low-frequency Ipicture but time is not available for playing back the low-frequency Ppictures, only the low-frequency I picture is played back. Further, inthe case where time is not available for playing back the whole Ipicture, the central part of the screen of the low-frequency I pictureis played back. In the aforementioned three cases, the optical head isallowed to jump to the front of the next GOP.

In the case where these addresses are described in the bitstreams, theaddress information is extracted and stored after the bitstreams areformed. In the case where these addresses are described in the privatedescripter of the program stream map, the address information isextracted and stored at the level of detecting the program streamheader. It goes without saying that the address information may beeither relative address of the program or the absolute address of theprogram.

In actually, as shown in FIG. 61, the mode signal for skip search,normal continuous playback or the like is inputted to the mode switcher76 from the microcomputer. In the meantime, the playback signal from thedisc is amplified by an amplifier and the signal is played back with aclock which is outputted from a PLL and in which the phase issynchronized. Then, the signal is digitally modulated and an error iscorrected to restore a program stream. Further, information is obtainedas to the data which follows the header by the program stream headerdetector 71 for detecting each head of the program stream.

Further, the address information for each picture and special playbackdata (low-frequency data and data arranged by the area of the screen)which are described in the private 2 packet of the PES packet isdetected by the PES packet header detector 72 and the information isstored in the address memory 75. Here it is judged whether the PESpacket is an audio PES packet, a PES packet such as characters, or avideo PES packet so that only the video PES packet is outputted to thevideo bitstream generator 73. The video bitstream generator 73eliminates the header removal of the PES packet to output thebitstreams. After this, in accordance with the address informationobtained from the address memory 75, the data rearranger 74 rearrangesthe bitstreams outputted from the mode switcher 76 and outputs thebitstreams in the normal playback.

The output (control signal) from the mode switcher 76 is supplied to thedata rearranger 74 and the decodable determiner 84. Here, the datarearranger 74 synthesizes the low-frequency component and thehigh-frequency component hierarchized and rearranged for each of theareas and outputs the synthesized components. In the meantime, eitherthe data only of the low-frequency component or the data only of thelow-frequency components at the central part of the screen are outputtedto the variable-length decoder 77 at the time of the special playback.In other words, at the time of the normal playback, the low-frequencycomponents of the I picture and the P pictures are rearranged in theorder of areas on the screen. Then the low-frequency components aresynthesized with the high-frequency components so that the device isoperated to rearrange the data in the original order of pictures. At thetime of the special playback, the area of the low-frequency componentsof the I picture at the central part of the screen and the area of thelow-frequency components of the I picture and the P picture at thecentral part of the screen are switched over to be outputted. The timestamp of the PTS and the DTS are not used at the time of the specialplayback which uses only the low-frequency components.

In contrast, the variable-length decoder 77 extracts the boundary of theevents in the low-frequency components region denoted by the prioritybreak point of the slice header together with the decodable determiner84 so that the data up to the boundary is decoded to be outputted to theswitch 78. The switch 78 is connected so as not to insert 0 at the timeof the normal playback. At the time of the special playback, the switch78 is controlled by the decodable determiner 84 so that 0 is insertedinto the high-frequency components after the priority break point.

An operation concept of the decoding of the low-frequency is the same asFIG. 44. An explanation thereof will be omitted. Further, at this time,the rearrangement on the screen area is the same as explained inembodiment 10. An explanation thereof will be omitted.

The coding area is defined at the boundary of the events, but it isneedless to say that the boundary of the events may be defined by othermethods. For example, the coding area may be divided by the end of apredetermined number of events, or the coding area may be defined bydividing the data by the data subjected to a rough quantization by thequantizer 54, and a differential value between the rough quantizationand a fine quantization. Further, the data may be divided with thecoding of the picture whose space resolution is decreased to the half bythinning and the picture whose resolution has been restored to theoriginal level from the half level and the differential picture with thepicture with the original resolution. In other words, it goes withoutsaying that the high efficiency coded data of the picture may be dividedby the division of the quantization and the space resolution in additionto the division of the frequency region.

At this time, more important data as a picture refers to the data in thelow frequency region in the case of the frequency division. In thedivision of by the quantization, the more important data refers to thedata coded by the rough quantization. In the case of the data divided bythe space resolution, the more important data refers to the dataobtained by coding a thinned picture. In such a case, with respect tothe playback picture decoded by using only these items of data, a regionwhich can be easily perceived by man constitutes the more importantdata. In other words, one high efficiency coded data is divided intomore basic and more important data and the data which is not importantso that the data which is basic and important is played back at the timeof the playback from the disc.

Embodiment 11 is described by corresponding the recording side to theplayback side. There may be a case where record and playback constitutea pair like a hard disc. Further, a case is considered wherein only theplayback side is given on a supposition that the data is recorded inaccordance with the presupposition like compact discs. Further, withrespect to the component rearrange for each of the areas of the screen,it goes without saying that a method for outputting a screen as shown inFIG. 54 and FIG. 55 in embodiment 10 is available. Further, it goeswithout saying that the rearrangement in the unit of area on the screencan also be realized with the prediction data decoding circuit 82 andthe frame memory 83 when the data of the slice vertical position in theslice header. Further, in embodiment 11, only the basic data of the Ipicture is divided by the area of the screen. It is needless to say thatthe data may be divided with the low-frequency of the P picture orothers.

Embodiment 12

Embodiment 12 of the present invention will be explained with respect toFIG. 63. FIG. 63 is a block diagram showing a digital video signalcoding processing unit in a digital video signal record and playbackdevice. In FIG. 63, reference numeral 101 and 104 denote preprocessors,102 and 105 motion vector detectors, 103 a resolution converter, 106 and107 subtracters, 108 and 109 DCT circuits, 110 and 111 quantizers, 112and 113 variable-length encoders, 114 and 115 inverse quantizers, 116and 117 inverse DCT circuits, 118 and 119 adders, 120 and 121 imagememories, 122 and 123 rate controllers, 124 a resolution inverseconverter and 125 a data reconstructor as a data arranging means.Further, FIG. 63 shows a first encoding means and a second encodingmeans as one example. In particular, the subtracter 106 outputs adifferential component between the first encoding means and the secondencoding means in the course of two coding.

Next, an operation of embodiment 12 will be explained. The video data isinputted to the resolution converter 103 in an order of the raster scanof the interlace. The inputted video data is filtered and thinned forpreventing repetitive noises in the high-frequency region with theresolution converter 103. FIG. 64 is an explanatory view explaining theconcept of this resolution conversion on the picture. For example, inthe case of the data of horizontal 704 pixels and vertical 480 pixels,the data is filtered followed by being thinned into horizontal 352pixels and vertical 240 pixels with a half resolution thereofrespectively thereby being converted into a low resolution screen data.

This low resolution screen data is converted from a raster scan into ablock scan by being inputted into the preprocessor 104. Here, the blockscan means that the data is sent in an order of the block of DCT. The Ipicture is coded without performing a calculation between frames usingthe output of the frame memory for intra-frame coding.

In the case of the I picture, the image memory 121 which is an input ofthe subtracter 107 outputs nothing so that the video signal passesthrough the subtracter 107. This data is orthogonally converted into thefrequency component by the DCT circuit 109. This orthogonally converteddata is inputted into the quantizer 111 and quantized in an order ofbeing scanned in a zigzag manner from the low frequency region. Further,the quantized picture data is converted into an entropy code via thevariable-length encoder 113 to be outputted to the data reconstitutingdevice 125.

In the meantime, the data quantized by the quantizer 111 is subjected tothe inverse quantization with the inverse quantizer 115. Then, thepicture data is inversely converted into data of a space component froma frequency component data by the inverse DCT circuit 117. The I pictureis decoded without calculation between frames performed by using theoutput of the frame memory which is subjected to the intra-frame coding.Consequently, in the case of the I picture, since there is no input fromthe image memory 121 of the adder 119, the data passes through the adder119. An output of the adder 119 is used as data stored in the picturememory 121. At least, the I picture data, or the I picture data and theP picture data is required to be stored in the picture memory. That isbecause the data of I picture and P picture is needed for decoding the Bpicture normally at the MPEG1 and MPEG2 as reference data.

Further, the image memory 120 inputs the output from the adder 118 ofthe decoded data and the result of the restored number of pixels byinterpolating the pixel by the resolution inverse converter 124 to storethe decoded data of the picture averaged with a certain weight. Withrespect to this weighting, there is described a case in which a weightof 1 is used as the output of the resolution inverse converter and aweight of 0 is used as the output of the adder 118 for simplicity.

Further, the input video data is buffered by the preprocessor 101 to bescan-converted from the raster scan to the block scan. Then, the videodata is subtracted by the subtracter 106 from the data of the imagememory 120 which stores a signal subjected to the aforementioned lowresolution processing (this is referred to as resolution residualcomponent). The resolution degree residual component is orthogonallyconverted into a frequency region to be converted into the scan from thelow-frequency region to be appropriately quantized by the quantizer 110.This data is coded into an entropy coded via the variable-length encoder112 and is outputted to the data reconstructor 125.

In the meantime, the data quantized by the quantizer 110 is inverselyquantized by the inverse quantizer 114 and is inversely converted in thedata in the space region at the inverse DCT circuit 116. The adder 118adds the input from the image memory 120 which is the inverselyconverted data subjected to the low resolution processing with converteddata with the output of the inverse DCT circuit 116 to obtain the resultof decoding of the data which is formed into two layers with the lowresolution data and the data of the residual component as one example ofthe data other than the low resolution data. This layer is determined bythe frequency of resolution conversion. It is possible to form the layerinto three layers by performing two resolution conversions. In the sameapproach, it is possible to prepare data in any number of layers withthe similar approach.

With respect to coding of the normal MPEG, the I picture and the Ppicture are decoded and stored as a decoded data to code the B pictureby performing a bidirectional prediction with the I picture and the Ppicture. In this manner, the I picture and the P picture are codedfollowed by the processing of the B picture.

The aforementioned coding processing of the I picture, P pictures and Bpicture are performed with respect to both the low resolution componentand the high resolution component. In this manner, a sequence can beconstituted wherein the low resolution component R (hereinafter referredto as R component) and the resolution residual difference component Sare arranged side by side. The operation is performed by the datareconstructor 125 so that the data is arranged at a place such as thefront of the GOP to which the optical head can favorably access. Forexample, the data is arranged as shown in sequence a of FIG. 65. Whenthe data is rearranged as shown in FIG. 65 and the half of the areawhich is occupied by the L component, the low resolution component canbe played back. The resolution residual difference component has asmaller data amount than the non-resolution residual differencecomponent, and the data can be efficiently hierarchized. In other words,here, a first encoding means for coding in accordance with predeterminedconditions and a second encoding means for coding the residualdifference of coding using the first encoding means as an example of avideo information other than coded by the first encoding means out ofvideo data are provided for an efficient hierarchization.

FIG. 65 is a view showing an example of the result of data constitution.In FIG. 65, a sequence a is a sequence generated by the codingprocessing of embodiment 12. A sequence b is a sequence generated by thecoding processing in another embodiment. A sequence c is a sequencegenerated by the coding processing in further another embodiment. In thesequence b, symbol L denotes a low frequency component, and H a highfrequency component. In the sequence c, symbol C denotes a componentcoded by a rough quantization, and A a residual component by the roughquantization, respectively. As shown in the sequence a in FIG. 70, theaforementioned operation is performed with respect to only the I pictureand P pictures. Only the component may be arranged in summary at thefront of the GOP.

In this manner, when only the low resolution component is arranged insummary at the front of the GOP, the ratio of the L component occupyingthe whole largely reduces so that an allowance can be made in thereading speed from the medium so that the skip search can be easilyrealized. In addition, like a sequence a, when only the R component ofthe I picture and the P picture are arranged in summary at the front ofthe GOP, the operation is performed so that only the low resolution dataof the I picture and the P picture are decoded. In the aforementionedembodiment, an explanation is given to a case in which the thinningratio is horizontal 1/2 times, and vertical 1/2 times. It goes withoutsaying the ratio can be set to a value different from the aforementionedvalue, but an arbitrary ratio can be applied to the embodiment.

Further, the coding mode includes the MPEG1, MPEG2 and JPEG or the like.In the hierarchization of the resolution, a common coding technique isnot necessarily adopted. That is because when the data is coded bylowering the resolution, it is possible to sufficiently correspond tothe coding with the MPEG1 mode. In addition, in the JPEG mode, thelamination of one frame on another constitutes a mobile picture.Consequently, it is possible to decode correctly the data even when thedata occupies a specific position of the GOP. In addition, theexplanation is given with respect to two degrees of resolution, but isgoes without saying that larger number of hierarchies can be used. Thedifferential component may be coded in the following manner: the data ofthe low resolution component is coded with the first encoding means inFIG. 63; the output from this first encoding means is interpolated; thedifferential component with the picture before thinning the pixels andthe interpolated data is obtained with the subtracter 106; and thedifferential component is coded by a differential component encodingmeans.

The frame read from the image memory is normally brought from theprediction reference frame. With the existence of the low resolutionframes, the data is required to be stored in the memory (including thememory address) by favorably adjusting the time axis. It goes withoutsaying that an information adding means may be provided to addadditional information such as an audio signal, a header or the like,and an error correction signal to the differential component.

Embodiment 13

Embodiment 13 of the present invention will be explained on the basis ofFIG. 66. In embodiment 13, the DCT block is divided into the layers of alow-frequency region and a high-frequency region so that only the lowfrequency region is arranged at the front of the GOP. FIG. 66 is a blockdiagram of the digital video signal coding processing unit. In FIG. 66,reference numerals 126 and 127 denote first variable-length encoder anda second variable-length encoder, respectively. Like parts orcorresponding parts in FIG. 66 are denoted by like numerals in FIG. 63,and an explanation thereof will be omitted.

Next, an operation will be explained. This interlace video data is adata item which has, for example, an effective screen size of horizontal704 pixels and vertical 480 pixels. Since the I picture is decodedwithout performing calculations between frames using the output of theframe memory subjected to the intra-frame coding, the video data ispassed through and outputted. This video data is orthogonally convertedinto the frequency component by the DCT circuit 108, and is convertedinto the block scan from the low frequency region. Then the video datais converted into a block scan from the low frequency region to beappropriately quantized by the quantizer 110.

The data arrangement of the DCT coefficient inside of the DCT block isshown in FIG. 67. In FIG. 67, a low frequency component is located at anupper part on the left and high frequency component is located at alower part on the right. Out of the DCT coefficient data arranged inthis DCT block, the DCT coefficient data (for example, a hatched part inFIG. 67) in the low-frequency region up to the data of the DCTcoefficient at a specific position is entropy coded via the firstvariable-length encoder 126 as a low frequency region extracting meansand is outputted to the data reconstructor 125. Further, the secondvariable-length encoder 127 performs the variable-length coding of thedata of the DCT coefficient after the data of the DCT coefficient at theaforementioned specific position. That is, in this manner, the data ispartitioned and coded in the frequency region.

With respect to the coding of the motion vector and the DC component,the coding may be performed only by the first variable-length encoder126. The second variable-length encoder 127 is not required. That isbecause at the time of the normal playback, the output data of the firstvariable-length encoder 126 and the output of the second variable-lengthencoder 127 may be synthesized and coded.

The determination of the coding region is performed at the fixedposition of the DCT coefficient. The determination can be made by othermethods. For example, the coding region may be determined with the fixednumber of events. In other words, a unit for providing a Huffman codewhich is a variable-length code is an event. The coding region may beset with a predetermined number of events such as a unit of three or thelike. In an example of the output bitstreams at the data reconstructor125 with the arrangement of sequence b in FIG. 65, the low frequencyregion picture can be played back when only the first half of thelow-frequency region is read. The coding region may be determined in avariable manner at the arrangement such as sequence b shown in FIG. 70.

In the meantime, the data quantized by the quantizer 110 is subjected toan inverse quantization. Then the data is inversely converted into thedata in the space region by the inverse DCT circuit 116. The I pictureis decoded without performing the calculation between frames using theoutput of the frame memory subjected to the intra-frame coding.Consequently, in the case of the I picture, there is no input from theimage memory 120 of the adder 118. Consequently, the data is allowed topass through the adder 118. The output of the adder 118 is used as datastored in the image memory 120.

At least, the I picture and the P pictures are required to be stored inthe image memory. That is because the data of the I picture and the Ppicture is normally required as reference data for the decoding of the Bpicture normally at MPEGs 1 and 2.

When constituted in this manner, the ratio of the L component largelyreduces so that an allowance can be made in the reading from the medium,enabling to realize a skip search. Further, as to be described later,when only the I picture and the P picture are arranged in summary, thedevice can be operated so that only the data of the low-frequencycomponent can be easily decoded. Since the data in the high-frequencyregion has smaller amount of data than all other regions of data, theefficient constitution of data can be made possible than extracting datain the low-frequency region and storing the data before the data in allthe regions.

When the coding of the I picture is ended by allowing the I picture topass through the subtracter 106, the B picture is coded in thebidirectional prediction with the last P picture in the GOP preceding nterms of time. The output of the preprocessor 101 and the data from thememory of the reference frame (arrow in the drawing omitted) arecompared with each other so that the motion vector is detected and theprediction mode and the frame structure are judged. On the basis of theresult of judgment, the data of the reference frame memory in which theoutput of the preprocessor 101 and the data from the reference framememory most favorably agree with each other is read as the data in theforward direction portion and the backward direction portion from theframe memory 120. Consequently, the data read in this manner and theoutput result of the preprocessor 101 of the B picture are subjected tosubtraction by the subtracter 106. (This result is referred to as timeresidual component with respect to both the P picture and the Ipicture). This time residual component is subjected to the DCTcalculation so that the result is quantized and is subjected to thevariable-length coding.

Embodiment 14

Embodiment 14 of the present invention will be explained on the basis ofFIG. 68. In embodiment 14, the data is divided into the roughquantization component of the DCT coefficient and the rough residualdifference component hierarchy as an example of the data other than therough quantization component so that the rough quantization component isarranged at the front of the GOP. FIG. 68 is a block diagram showing adigital video signal coding processing unit. In FIG. 68, referencenumeral 128 denotes a subtracter and 129 an adder. Like parts orcorresponding parts in FIG. 68 are denoted by like numerals in FIG. 63,and an explanation thereof will be omitted.

Next, an operation of embodiment 14 will be explained. The input pictureof this interlace has, for example, an effective screen size ofhorizontal 704 pixels and vertical 480 pixels. The I picture is decodedwithout performing the calculation between frames using the output ofthe frame memory which is subjected to the intra-frame coding.Consequently, in the case of the I picture, nothing is inputted to thepicture memory which is the input of the subtracter 106 with the resultthat the video signal passes through the subtracter 106. This data isorthogonally converted into the frequency component and the DCT circuit108, and is converted into the block scan from the low frequency region.Then, the quantizer 110 performs an appropriate rough quantization whichreduces the coded data amount to less than half. This quantized data iscoded into an entropy code via the variable-length encoder 112 to beoutputted to the data reconstructor device 125.

In the meantime, the data quantized by the quantizer 110 is subjected toinverse quantization (the result is referred to as the result of therough quantization). The data subjected to the inverse quantization issent to a different coding processing unit (part denoted by a dot lineframe in FIG. 68). In the meantime, the data is inversely converted intothe data in the space region. Here, the coding of the I picture isdescribed. Although there is no output from the image memory 121, innormal cases, the coding result at this coding processing unit is storedin the image memory 121 so that the data is subjected to motion vectordetection at the motion vector detector 102, the prediction mode isdetermined and the DCT block mode is determined. The position datasuitable for the determined mode is referred to, and is inputted to thesubtraction input side of the subtracter 107.

The output of the subtracter 107 is subjected to the DCT to determine aresidual difference (which is referred to as a rough quantizationresidual difference) with the result of the rough quantization and thesubtracter 128. The rough quantization residual difference is finelyquantized (fine quantization on the same level as the normal coding inconsideration of the coding amount control) to perform thevariable-length coding while being inversely quantized, subjected to theinverse DCT and decoded to be stored in the image memory 121. The resultof this coding and the coding result of the rough quantization determinethe allocation of necessary data and a header or the like is added.

As an example of this output data, the sequence c shown in FIG. 65 isadopted, the decoding result of the picture which is subjected to therough quantization is obtained only by reading the first half of theGOP. In addition, since the data of the rough quantization residualdifference is small compared with finely quantized data, a moredata-efficient constitution can be obtained than storing the extractedrough quantization data before the fine quantization data.

Further, as another example, variable processing such as an arrangementof the sequence c shown in FIG. 70 may be performed. Thus constituted,the ratio of the C component (component coded by performing the roughquantization) out of the whole largely reduces so that an allowance canbe made in the reading speed from the medium to enable a skip search orthe like. Further, as will be described later, when the only the Ipicture and the P picture are arranged in summary, the device of theinvention is operated so that only the data which is subjected to therough quantization of the I picture and the P pictures is decoded.

When the coding of the I picture is ended by allowing the I picture topass through the subtracter 106, the B picture is coded withbidirectional prediction with the last P picture in the preceding GOP interms of time. An output of the preprocessor 101 is compared with thedata (arrows are omitted in FIG. 70) from the memory of the referenceframe so that the motion vector is detected and the prediction mode andthe frame structure are judged. On the basis of the result of judgment,the data in the reference frame memory in which the output of thepreprocessor 101 most favorably agrees with the data from the referenceframe memory is read as data in the forward direction portion and thebackward direction portion from the image memory 120 so that the datathus read and the output result of the preprocessor 101 of the B pictureare subtracted by the subtracter 106 (this result is referred to as timeresidual difference component for both P picture and B picture). Thedata in the forward direction portion and in the backward directionportion is read from the picture memory 121 so that the data and theoutput of the preprocessor 101 is subtracted by the subtracter 107 fororthogonal transform entropy coding. The same process is performed withrespect to the P picture for coding the P picture.

FIG. 69 is a view showing an example of a statistical amount of thecoded data, the view showing a distribution of the code amount at thetime when the number of frames in the GOP: N=15 and cycle of the Ipicture and the P picture: M=3. It is shown in FIG. 69 that the Ipicture and the P picture account for about 50% of the whole. When thehierarchy is divided with the resolution, the frequency, and thequantization at least with respect to this part or the I picture asdescribed above, the code amount which is to be played back furtherreduces so the travel time of the optical head can be shortened therebyfacilitating the realization of the functions such as the skip search orthe like.

FIG. 70 shows a processing sequence in the above-mentioned case. In FIG.70, an arrangement of the I picture, P pictures and B picture of theoriginal picture are coded so that the processing described inembodiments 12, 13 and 14 are performed only with respect to the Ipicture and the P pictures out of the aforementioned pictures while theB picture is coded without hierarchization. A sequence in which the Ipicture and the P picture are processed in accordance with theprocessing shown in embodiment 12 is referred to as sequence b while asequence in which the I picture and the P picture are processed inaccordance with the processing shown in embodiment 14 is referred to assequence c.

In each sequence, the data is constituted by fixing and arranging insummary at the front of the GOP the I picture component and the Ppicture component of respective low resolution components (R), the lowfrequency components (L) and the rough quantization component (C) byrespective data reconstructor device 125. With the sequence a, the lowresolution picture of the I picture and the P picture can be decodedonly with the low resolution component (in the sequence a of FIG. 70,core area portion after the data reconstruction) of the I picture and Ppicture with the result that the device can easily cope with skipsearch. Naturally, the data in the area other than the core area is notrequired to be arranged as shown in FIG. 70. It goes without saying thatthe data may be arranged in an order of frame numbers at the time ofencoding.

With respect to the sequence b, the low frequency component of the Ipicture and the P picture can be formed only with the low frequencycomponent (core area part after data reconstitution in the sequence b ofFIG. 70) so that the device is capable of easily coping with the skipsearch. With respect to the sequence c, rough quantization picture ofthe I picture and P picture can be decoded only with the roughquantization component of the I picture and P picture (the core areapart after data reconstruction in the sequence c of FIG. 70) so that thedevice can easily cope with the skip search. With respect to thesequence c, rough quantization picture of the I picture and P picturecan be decoded only with the rough quantization component of the Ipicture and P picture (the core area part after data reconstruction inthe sequence c of FIG. 70) so that the device can easily cope with theskip search.

For example, in a structure shown in FIG. 63, a coding loop includingthe reprocessor 104 is not used for the B picture so that the device maybe operated in such a manner that the data is coded only with a codingloop including the preprocessor 101. In a structure shown in FIG. 66,all frequency components may be coded with the first variable-lengthencoder 126. Further, in a structure shown in FIG. 68, a finequantization may be performed at the quantizer 110 for coding the data.

Most ideally, the basic data such as low frequency side data may becollected at the front of the GOP. It goes without saying that the datamay be shifted a little so that the data may be overlapped with thefront of the unit which constitutes an error correction code. Arrangingthe basic data corresponding to the unit of the error correction code inthis manner can be practiced in the same manner in other embodiments.

Embodiment 15

Embodiment 15 of the present invention will be explained with respect toFIG. 71 and FIG. 12. FIG. 71 is a view showing the arrangement of DCTblocks and an example of an arrangement outline of the frequencycomponent in bitstreams of one block. FIG. 71A shows that one macroblockis formed of the header of the macroblock, the DCT blocks Y1 to Y4 of aluminance signal, a DCT block U1of a color difference signal (B-Y) and aDCT block V1of a color difference signal (R-Y) with respect to thearrangement of the whole DCT block. FIG. 71B shows that onelow-frequency component of the macroblock is formed with the macroblockheader, the DCT blocks Y1L to Y4L of a luminance signal, the DCT blockU1L of the color difference signal (B-Y) and a DCT block V1L of a colordifference signal (R-Y) with respect to an arrangement of alow-frequency component DCT block.

Further, FIG. 71C shows that one high-frequency macroblock is formedwith the DCT blocks Y1H to Y4H of a luminance signal, the DCT block U1Hof the color difference signal (B-Y) and the DCT block V1H of the colordifference signal (R-Y) with respect to an arrangement of the high areacomponent DCT block. FIG. 71D shows a concept of an arrangement offrequency component data in bitstreams of one block. FIGS. 72A and 72Bare a block diagram showing a digital video signal decoding processingunit, and a view showing an operation concept thereof. In FIG. 72A,reference numeral 130 denotes a mode switcher as a mode switching means,131 a data rearranger as a data rearranging means, 132 a decodabledeterminer, 133 a variable-length decoder and 134 a switch. Thedecodable determiner 132 and the switch 134 constitute a data operatingmeans. Reference numeral 135 denotes an inverse quantizer, 136 aninverse DCT circuit, 137 an image memory, 138 an adder, and 139 aninverse scan converter.

Next, an operation will explained. The data shown in FIG. 71 is a codearrangement assembled in 8 bits (1 byte) for example, in the verticaldirection. In arch macroblock, information is described with respect tothe macroblock which is referred to as the macroblock header. Thisinformation refers to, for example, an increment address, a quantizationscale code, a motion vector, a marker bit, a macroblock pattern or thelike.

The coded data of each DCT block follows this macroblock header. Amethod for embedding this data is constituted so that a byte isconstituted with bitstreams to arrange each byte in order. Since eachDCT block has a variable code length, the block boundary and theboundary between the header and the data is not completed in the unit ofbytes. It often happens that the boundary exists in the midst of oneunit of byte. The data in each block has a variable length, and alower-frequency region is provided at a position nearer to the side ofthe macroblock head.

This data is divided into the a low frequency component (L) and ahigh-frequency component (H) to constitute a coded data as shown in FIG.71B and 71C by setting a fixed length code amount which is irrelevant tothe event as a maximum value (the event is a unit for providing onevariable-length code, and in the case of the DC component, the DCcomponent constitutes one event while in the case of the AC component acombination of non-zero DCT coefficient and the run length constitutesone event for performing run length coding. One event completes with acode referred to as EOB at the end of the block).

Next, an operation shown in FIG. 72 will be explained. In the beginning,a mode signal is inputted from a microprocessor or the like to the modeswitcher 130, the signal indicating that the skip search is beingperformed, or the normal continuous playback being performed. In themeantime, the playback signal from the disc is amplified with anamplifier, and is digitally demodulated to perform an error correctionby performing a differentiation operation from an output data obtainedafter a signal playback is performed with a clock which is subjected tophase synchronization and is outputted from a PLL or the like, followedby separating an audio signal from a layer of a certain system whichconstitutes video signal data and audio signal data. Then the bitstreamof the video signal is extracted and is inputted to the data rearranger131.

The output (control signal) of the mode switcher 130 is supplied to thedata rearranger 131 and the decodable determiner 132. The datarearranger 131 obtains a control signal and reconnects the data beforedivision from an L component and an H component shown in FIG. 71, oroutputs only the L component to the variable-length decoder 133. Thevariable-length decoder 133 extracts a boundary of events in the Lcomponent region together with the decodable determiner 132. The portionup to the boundary is decoded and outputted to the switch 134. Thisswitch 134 is connected so that no zero is inserted at the time of thenormal playback. The switch 134, which is controlled with an output ofthe decodable determiner 132 inputs the decoded low-frequency componentto the DCT block. In the meantime, the whole DCT block is constituted sothat a zero is inserted into the high-frequency side of the DCT block.

At the time of decoding, the data of the DCT block constituted in theaforementioned manner is subjected to the inverse DCT process. Then, thereading of the image memory 137 is controlled in accordance with thecases of respective pictures to be added by the adder 138. In the caseof the I picture, the output of the adder 138 is passed through. In thecase of the P picture, the P picture is corrected only by the motionvector of the I picture and P picture to be added. In the case of the Bpicture, the B picture is corrected by the motion vector from both the Ipicture and the B picture to be added.

Further, the DCT mode and the prediction mode motion vector at this timeare controlled on the basis of information obtained by decoding theheader code. In accordance with the aforementioned process, the datawhich is subjected to the motion compensation prediction is decoded andis stored in the image memory 137. The picture is restored to theoriginal constitution order of the GOP. The inverse scan converter 139converts the buffering and the block scan into the raster scan in theoutput order of the picture.

Embodiment 15 is represented to be fixed in length even when theembodiment is shorter than the skip of the macroblock or thepredetermined fixed length data. However, even when the length isshorter than the fixed length, the L component can be taken out withcertitude by detecting the EOB every time. Consequently, it goes withoutsaying that no problem is caused even when the L component data isconnected to the subsequent block. Further, the EOB may be attached tothe event demarcation as the L component data when the length exceedsthe predetermined length. Further, it goes without saying that aninformation adding means for adding additional information such as anaudio signal, a header or the like and a correction code is furtherprovided to be added to the data in the high-frequency region though notparticularly shown in the figures in the explanation of theaforementioned embodiments.

Embodiment 16

Next, embodiment 16 of the present invention will be explained byreferring to FIG. 73 and FIG. 74. FIGS. 73A and 73B are a block diagramof a digital video signal coding processing unit and a view showing anoperation concept thereof. In FIG. 73A, reference numeral 140 denote arate controller. Here, as encoding means, a first variable-lengthencoder 126 and a second variable-length encoder 127. Like parts orcorresponding parts are denoted by like numeral in FIG. 63.

Next, an operation will be explained. An interlace input picture data isbuffered with the preprocessor 101 to convert a raster scan into a blockscan. The I picture is decoded without performing a calculation betweenframes using an output of the frame memory which is subjected to theintra-frame coding. Consequently, in the case of the I picture, nothingis inputted to the image memory 120 which is an input of the subtracter106 so that the video signal passes through the subtracter 106.

This data is orthogonally converted into the frequency component by theDCT circuit 108,. and is converted from the low frequency region intothe block scan to be subjected to an appropriate quantization by thequantizer 110. A low-frequency region data up to the data of the DCTcoefficient at a specific position out of this quantized data is subjectto entropy coding and outputted to the data reconstructor 125 via thefirst variable-length encoder 126.

Further, the second variable-length encoder 127 performs thevariable-length coding of the DCT coefficient after the data locatedafter the aforementioned specific position. With respect to the codingof the motion vector and the DC component, only the firstvariable-length encoder 126 may be used at least. It is required thatthe EOB is added both to the L component and to the H component even inone block so that the boundary of the L component changes at rateswithout limitations of codes. The boundary of the L component can bechanged at a rate by temporarily arranging an EOB code at a demarcationpart of the L component and the H component.

In the meantime, the data quantized by the quantizer 110 is subjected tothe inverse quantization by the inverse quantizer 114 to be inverselyconverted into a space component data by the inverse DCT circuit 116.

The I picture is decoded without performing a calculation between framesusing an output of a frame memory which is subjected to the intra-framecoding. Consequently, in the case of the I picture, since nothing isinputted from the image memory 120 to the adder 118, the data is allowedto pass through the adder 118. The output of the adder 118 is used asdata stored in the image memory 120. At least the I picture, or the Ipicture data and the P picture data are required to be stored in theimage memory 120. That is because the I picture and the P picture dataare required for decoding the B picture normally in the MPEG 1 and theMPEG 2 as reference data.

When the coding of the I picture is ended, the B picture is coded in thebidirectional prediction with the last P picture in the preceding GOP.Then, the output of the preprocessor 101 is compared with the data(arrows in the drawings omitted) from the reference frame memory todetect the motion vector and to judge the prediction mode and the framestructure. On the basis of the result of judgement, the data in thereference frame memory in which the output of the preprocessor 101 ismost suitable with the data from the reference frame memory in thereference frame memory is read from the image memory 120 together withthe data in the forward direction portion and in the backward directionportion. The data and the output result of the preprocessor 101 aresubtracted by the subtracter 106 (the result is referred to as timeresidual difference component with respect to the P picture and the Bpicture). This time residual difference component is subjected to DCTprocess, quantization and variable-length coding process.

When the data is divided into the low-frequency region and thehigh-frequency region, the rate becomes indefinite in the frequencycomponent. Consequently, since the data rate in the low-frequency regiondoes not become definite, the scope in which an actuator of the head canbe controlled cannot be completely compensated for. Here, the ratecontroller 140 renders the low-frequency component region variable. Therate controller 140 controls the rate so that a size of thelow-frequency region becomes variable with respect to the target rate asshown in FIG. 73B.

In other words, while monitoring the output of the first variable-lengthencoder 126, the rate controller 140 reduces the size of the areaoccupied by data in the low-frequency region when the monitored outputis larger than the target rate set by the application. When the codeamount of the first variable-length encoder 126 is small, the ratecontroller 140 enlarges the area of the low frequency region. In thismanner, while monitoring the code amount, the rate controller 140appropriately changes the setting of the occupied area in thelow-frequency region with respect to the first variable-length encoder126 and the second variable-length encoder 127.

Additionally, for example, a temporary coding may be performed todetermine the standard for setting of the occupied area of thelow-frequency region from the result as to which region has largernumber of codes and which region has smaller number of codes therebysetting the target rate.

FIG. 74 is a block diagram of a digital video signal decoding processingunit, a view showing the decoding processing for decoding data coded asdescribed above. In FIG. 74, reference numeral 141 denotes an EOBretrieval unit. Like parts or corresponding parts are denoted by likenumerals in FIG. 72A. A mode signal indicative of a state such that thedata is being skip searched or the normal continuous playback is beingoperated is inputted from a microcomputer or the like to the modeswitcher 130. In the meantime, a playback signal from the disc isamplified by an amplifier so that the playback signal is differentiatedwith a clock which is subjected to PLL, for digital demodulation. Anaudio signal is separated from a system layer by conducting an errorcorrection to extract video bitstreams to be inputted to the datarearranger 131. The output of the mode switcher 130 as mode switchingmeans is supplied to the data rearranger 131 and the decodabledeterminer 132. The data rearranger 131 obtains this control signal tobe operated so as to connect the data before the division from the Lcomponent and H component shown in FIG. 71. Otherwise, only the Lcomponent is outputted to the variable-length decoder 133 which servesas a decoding means without being connected to the H component.

Theoretically, it never happens that the L component is severed in themidst of the events. In consideration of a case where the signal qualitysuch as skip search or the like is not favorable, the boundary of theevents is confirmed with the variable-length decoder 133 and thedecodable determiner 132 so that the portion up to the boundary isdecoded and outputted to the switch 134. The switch 134 is operated insuch a manner that it is always turned on with respect to the playbackdata with a good signal quality like at the normal playback. Here, thedecodable determiner 132 and the switch 134 constitute a data operatingmeans.

The switch 134 is controlled with the decodable determiner 132 so that azero is inserted into the high-frequency side of the of the block fromthe low-frequency component which has been successfully decoded therebyconstituting the DCT block. Then, the data is subjected to inverse DCTso that the output of the adder 138 is passed through with respect tothe case of the I picture. In contrast, with respect to the P picture,the data is corrected and added by the portion of the motion vector inthe I picture of the reference. With respect to the B picture, thereading of the image memory 137 is controlled and added by the adder 138so that the B picture is corrected by the portion of the motion vectorfrom the I picture and the P picture to be added. The DCT mode, and theprediction mode motion vector are controlled by decoding a code of theheader. The data which is subjected to motion compensation prediction inthis manner is decoded and is stored in the image memory 137. Then, thepicture is rearranged into the original constitution order. The inversescan converter 139 buffers the data and converts the data in the outputorder from the block scan to the raster scan.

Further, in the aforementioned explanation, an example is explained inwhich a size of the DCT coefficient is controlled. The number of eventsmay be controlled instead. In this case, it sometimes happens that the Lcomponent does not attain a predetermined number of events and EOB isadded. However, since the EOB retrieval unit 141 monitors the appearanceof the EOB, the L component can be detected with certitude. Here, inparticular, the data is reconstituted on the basis of the data in thelow-frequency region, the data in the high-frequency region, and the EOBrespectively. That is, the data rearranger 131 and the EOB retrievalunit 141 constitutes a data reconstructing means.

Since the energy after the DCT is naturally small, it goes withoutsaying that the L component and the H component are desirably coded inthe same manner with respect to the non-coded block which is not coded.With respect to the H components the data excluding the L component isideally run-length coded. BY setting the L component to 0, the Hcomponent may be coded. Since it is possible to cope with the structuresame as the variable-length decoder of the normal MPEG, this one can besimplified in terms of circuits.

Embodiment 17

Embodiment 17 of the present invention will be explained on the basis ofFIG. 75. FIG. 75 is a block diagram showing a digital video signaldecoding processing unit. In FIG. 75, reference numeral 142 denotes amultiplexer, 143 a switch, 144 a first variable-length decoder, 145 asecond variable-length decoder, 146 a first inverse quantizer, 147 asecond inverse quantizer, 148 and 149 adders, 150 and 151 imagememories, and 152 resolution inverse converter. FIG. 75 also shows a lowresolution decoding unit as decoding means. Like parts or correspondingparts are denoted by like numerals in FIG. 72A and an explanationthereof is omitted.

Next, an operation of embodiment 17 will be explained. What is shown inFIG. 75 may be considered as corresponding to the processing block ofthe video data of a playback signal from the disc in the case where thecoded data as described in FIG. 68 is recorded on an optical disc or thelike. A mode signal indicative of a state such that a skip search isbeing performed or normal continuous playback is being performed isinputted from a microcomputer or the like to the mode switcher 130 as amode switching means. In the meantime, the playback signal from the discis amplified at the amplifier and a playback signal is differentiatedwith a clock subjected to PLL for digital demodulation. Then an audiosignal is separated from the system layer to extract video bitstreams.

This extracted video bitstream is inputted to the multiplexer 142. Themultiplexer 142 sends the data of the low resolution component to thesecond variable-length decoder 145 while sending the other data to thefirst variable-length decoder 144 via the switch 143.

The switch 143 is controlled by the mode switcher 130. As a mode,although only the output of the playback picture of the low resolutioncomponent is demanded at the skip search or the like, the switch 143 isoperated to suspend the sending of redundant data in the case where theresolution residual difference component is played back halfways.Further, at the time of the normal playbacks the switch 143 remainsconnected.

The second variable-length decoder 145 decodes a Huffman code and therun length code to be inversely quantized by the second inversequantizer 147 and is converted from a frequency component into a spacecomponent by the inverse DCT circuit 136.

With respect to the I picture, the converted data is passed through theadder 149 to be stored in the image memory. In the case of the Ppicture, the first frame of the P picture is read from the I picturestored in the image memory and the P picture of the second frame orafter is referred to the preceding P picture stored in the image memoryand corrected by the motion vector portion to be subjected to the motioncompensation prediction by the adder 149. In the case of the B picture,the same operation is performed on the basis of the I picture and the Ppicture.

In FIG. 75, a motion vector, a quantization parameter for inversequantization and a prediction mode are outputted from thevariable-length decoder. Such a motion vector, a quantization parameterand the a prediction mode are the same as shown in FIG. 74. A loop shownby a dot line block in FIG. 75 is a constitution unit for decoding a lowresolution component. Since the decoding result is interpolated betweenpixels by the resolution inverse converter 152 as interpolation videogenerating means to compensate for the decoding result as resolutionresidual difference component, the decoding result is inputted to theimage memory 150.

The decoding of the resolution residual component at the time of thenormal playback is outputted as a picture by the inverse scan converter139 in combination with the decoding result of the low resolutioncomponent (or in accordance with the division processing in the casewhere the decoding of the resolution residual component is performed bytime division). The data can be decoded into the frequency component bythe first variable-length decoder 144 via the switch 143. The firstinverse quantizer 146 inversely quantizes the data and the inverse DCTcircuit 136 decodes data into the resolution residual differencecomponent data in the space region.

The image memory 150 refers to the pixel interpolation data of the lowresolution component, and further the P picture refers to the I picture,the B picture refers to the I picture and the P picture so that the datais corrected in position by the motion vector portion with the resultthat the data is read from the image memory 150, and the motioncompensation prediction is decoded by the adder 148.

Further, in the case of the skip search, to prevent the resolutionresidual difference component from being played back halfways,superfluous data is prevented by the switch 143 from being outputtedfrom the inverse DCT circuit 136, by suspending the output of theresolution residual difference. Consequently, only the pixelinterpolated data of the low resolution component is outputted (theoperation will be the same even if a switch is provided on the inputpart of the image memory 150) via the image memory 150 and via theinverse scan converter 139.

Embodiment 18

Embodiment 18 will be explained with respect to FIG. 76 and FIG. 77.FIG. 76 is a block diagram showing a GOP address generating unit and adisc control unit, the diagram showing, in particular, a processingblock in the case of recording the aforementioned rate information on asequence header. In FIG. 76, reference numeral 153 denotes a register,154 a GOP address calculator, and 155 an optical head/disc rotationcontrol converter as a head position converting means and as a discrotation control converting means. Further, FIG. 77 is a block diagramshowing a GOP address generating unit and a disc control unit includinga playback processing, the diagram showing, in particular, a structurefor performing a GOP playback from a disc on which the aforementionedrate information is collected at several places. Referring to FIG. 77,reference numeral 156 denote a playback amplifier, 157 a digitaldemodulator, 158 an error corrector, 159 a system layer processor, and160 a rate data memory. The system layer processor 159 and the rate datamemory 160 constitute a data rate information extracting means.Reference numeral 161 denotes a GOP number counter. The GOP addresscalculator 154 and the GOP number counter 161 constitute a positioninformation calculating means.

Next, an operation of embodiment 18 will be explained. An overall rateof one program can be optimized by rendering the rate per one GOPvariable as described in the conventional example with the result thatthe quality of the picture can be considerably improved. However, it isnot apparent that the data falls on the front of the GOP until watchingthe data content. Also, in the case where it is desired that thesoftware which has been matched halfway be played back again from thatposition, only way is to detect the starting position by retrieving thedata on the disc minutely.

Here, in such a case, the rate control of the variable rate is set, inthe beginning, to discrete rate goals such as 1 Mbits, 1.5 Mbits, 2Mbits, 2.5 Mbits, 3 Mbits or the like so that each of the rateinformation in all the GOP is recorded on a disc. In particular, itwould be most effective when the rate information with respect to eachGOP is recorded on a TOC (Table of Content: a record region is assignedto the very beginning of the disc so that information such as the title,the recording time or the like is recorded), a semi-TOC or the like.

Further, the rate information with respect to GOP may be assembled inthe sequence header of video bitstreams. For example, two hour software14.4 k pieces of GOP. The rate information at this time may berepresented with 3 bits when the rate information can be divided intofive kinds of rates. Consequently, all the GOP rates can be recorded onthe disc with 5.4 k (14.4 k pieces×3 bits/8 bits/bytes.

A nigh speed access can be made to a desired GOP by storing the rateinformation of each of the GOP in the rate data memory 160 shown in FIG.77 and adding up the information length corresponding to the value.

The device will be explained with respect to FIG. 76. The Huffman code,the run length code are decoded and the header is deciphered so that themotion vector and the kind of picture are judged.

In the meantime, the sequence header is decoded so that the rateinformation is inputted to the GOP address calculator 154. In addition,the address information of the GOP which is currently accessed to isstored in the register 153 so that the GOP front address for the nextaccessed is calculated and stored in the register 153. At the same time,by using the optical head/disc rotation control converter 155 up to thefront of the next GOP to be accessed, the position of the optical headis determined on the basis of the address. Then a control signal to thenext access is calculated from a difference between the GOP which isbeing accessed and the front address to be accessed. Based on thiscontrol signal, the position control of the optical head actuator andthe control of the disc rotation will be performed.

The playback processing will be explained by referring to FIG. 77. Theoptical head and the optical head rotation are controlled so as to readthe data either directly or indirectly from the TOC region or the regioncorresponding to the TOC region (after the rate information descriptionaddress is designated, this address portion is accessed to read the rateinformation). Then, the playback signal from the optical head isamplified with a playback amplifier 156 to detect the wave of thissignal by the digital demodulator 157 to differentiate the signal intothe digital signal for digital demodulation.

The playback signal which is digitally demodulated into a digital signalis inputted into the error corrector 158 to correct an error included inthe playback signal. The data after the error correction is separatedinto the audio bitstreams, video bitstreams and other data items by thesystem layer processor 159.

For example, it is judged which kind of data (AV (video and audio) data,text data and binary data such as program or the like) this signalbelongs to cut and classify the stream channel. In such a process, theaforementioned rate information is stored in the rate data memory 160.

In contrast, information as to which number of GOP is desired to beprocessed is generated by using the GOP number counter 161. On the basisof the address calculated by the GOP address calculator 154 the opticalhead actuator and the disc rotation speed of the disc are controlled. inthe aforementioned explanation, an example is given in which the GOPnumber counter 161 receives a signal from the system layer processor159. In the case where a part which the user I/F such as themicrocomputer substitutes a processing or in the case where theoperation moves from the playback to the skip search, it would be moreefficient to input address data from a variable-length decoder or thelike for processing the video bitstream.

Embodiment 19

Next, embodiment 19 of the present invention will be explained based onFIG. 78, FIG. 79 and FIG. 80. An operation will be explainedhereinbelow. FIG. 78 is a view showing a signal processing unit in thecase in which the division by the frequency of the digital signalplayback unit and the division by the quantization are performed, theview being a block diagram of a structure used in the playbackprocessing in the case where the rate information is collected andrecorded at several places on the disc. Like parts or correspondingparts are denoted by like symbols in the aforementioned embodiments inthe drawings.

The optical head or the optical head rotation are controlled so that thedata is either directly or indirectly read from the TOC region or theregion corresponding to the TOC region (the rate information descriptionaddress is designated). The playback signal is amplified with theplayback amplifier 156. Then, this signal is detected by the digitaldemodulator 157 to be differentiated for digital demodulation.Consequently, the playback signal which becomes a digital data isinputted to the error corrector 158 to correct an error included in theplayback signal. The data free from errors is separated into audiobitstreams and video bitstreams by the system layer processor 159 andother data is processed as well.

For example, it is judged which kind of data (AV) data, text data, orbinary data or the like such as programs) this signal belongs to divideand classify stream channels. Out of them, the aforementioned rateinformation is stored in the rate data memory 160. In contrast,information is generated as to which number of the GOP is desired to beprocessed is generated by using the GOP number counter 161. Then theaddress is calculated by the GOP address calculator 154. On the basis ofthe address calculated by the GOP address calculator 154, the opticalhead actuator and the rotation speed of the disc are controlled.

In this manner, at the time of skip playback, skipping is performed onthe disc to find the address of the GOP to be accessed. When theskipping is performed to make an access to a desired GOP, low-frequencyregion data obtained by using a structure described, for example, inembodiment 16 is played back and described on the screen whilecalculating the next address in the same manner.

A mode signal indicative of the state such that the data is being skipsearched or a normal playback is being continuously performed isinputted from a microcomputer to the mode switcher 130. As describedabove, the video bitstream is extracted to be inputted into the datarearranger 131. The output of the mode switcher 130 is supplied to thedata rearranger 131 and the decodable determiner 132. The datarearranger 131 obtains such a control signal to operate so that the databefore division is reconnected from the L component and the H componentin FIG. 71. Otherwise, the data rearranger 131 outputs only the Lcomponent to the variable-length decoder 133 without connecting the Lcomponent to the H component.

In embodiment 19, theoretically it does not happen that the L componentis cut in the midst of -the event. However, considering the case where asignal having an unfavorable signal quality of the skip search or thelike is decoded, the boundary of the event is confirmed with thevariable-length decoder 133 and the decodable determiner 132 forassurance so that a portion up to the boundary is decoded and outputtedto the switch 134.

The switch 134 is controlled with an output from the decodabledeterminer 132 so that a zero is inputted to the high-frequency side ofthe block from the low-frequency component which has been successfullydecoded to constitute the DCT block. Then the reading of the imagememory 137 is controlled and added by the adder 138 so that the data issubjected to the inverse DCT in such a manner that the output of theadder 128 is passed through in the case of the I picture and the data iscorrected by the motion vector portion to be added in the case of the Ppicture and the data is corrected by the motion vector portion from theI picture and the P picture and is added in the case of the P picture.

Further, the DCT mode and the prediction mode motion vector at this timeare controlled by decoding the header code. In this manner, the datasubjected to the motion compensation prediction is decoded and stored inthe image memory 137 to constitute the picture in the originalconstitution order. At the inverse scan converter 139, the data isbuffered to convert the data from the block scan to the raster scan inthe output order of pictures. In addition, the switch 134 is notconnected so that a zero is inserted at the time of the normal playback,but is controlled to operate and play back only the playback data.

Further, in the case where the data is divided and coded into the lowfrequency region and the high frequency region, there may be cases inwhich a quantization table which places an emphasis on the low frequencyside, a quantization table which places an emphasis on the highfrequency side, and a fine quantization irrespective of the frequencyregion quite evenly with respect to one quantization table are prepared.Such a case can be realized when two sets of the variable-length decoderand the inverse quantizer are provided as can be seen in the localdecoder shown in FIG. 68. At that time, the data rearranger 131 has tobe a multiplexer.

Next, an operation of embodiment 19 will be explained on the basis ofFIG. 79. FIG. 79 is a view showing a signal processing unit in the casewhere division by the bit length of the digital signal playback unit isperformed, the view being a block diagram for explaining an embodimentwith respect to the playback processing in the case where theaforementioned rate information is collected and recorded particularlyat several places on the disc. For example, at the very beginning of theplayback of the disc which is a predetermined region on the recordingmedium, the optical head and the optical head rotation is controlled sothat data is directly or indirectly read from the TOC region or a regioncorresponding to the TOC region (designating the rate informationdescription address), and the playback signal from the optical head isamplified with the playback amplifier 156 so that this signal isdetected with the digital demodulator 157 to be differentiated into adigital signal for digital demodulation.

As a consequence, the playback signal which has become a digital data isinputted to the error corrector 158 to correct an error included in theplayback signal. The data free from errors is separated into audiobitstreams and video bitstreams and other data items are processed aswell.

For example, this signal judges whether the data is video audio data,text data or binary data of programs or the like to cut and classify thestream channel. Out of such data, the aforementioned rate information isstored in the rate data memory 160. In the meantime, information isgenerated by the GOP number counter 161 as to which number of the GOP isdesired to be processed, and the address is calculated by the GOPaddress calculator 154 to control the actuator and the rotation speed ofthe disc.

In this manner, the address of the GOP to be accessed at the time of theskip playback is searched for by skipping on the disc. When the desiredGOP is accessed, the next address is calculated in the same manner andat the same time the data of the low frequency region obtained by usingthe structure described, for example, in embodiment 15 is played back torepresent the data in one screen.

A mode signal indicative of the state such that the skip search is beingperformed or a normal continuous playback is being performed is inputtedto the mode switcher 130 from the microcomputer or the like. The videobitstream is extracted and is inputted to the data rearranger 131. Anoutput of the mode switcher 130 is supplied to the data rearranger 131and the decodable determiner 132. The data rearranger 131 obtains thiscontrol signal to operated to reconnect data before the division fromthe L component and the H component of FIG. 71. Otherwise, the datarearranger 131 outputs only the L component to the variable-lengthdecoder 133 without connecting the L component to the H component.

The variable-length decoder 133 and the decodable determiner 132 extractthe boundary of the events in the L component so that the portion up tothe boundary is decoded and outputted to the switch 134. The switch 134is controlled by the output of the decodable determiner 132 so that azero is inserted to the high-frequency side of the block from thelow-frequency component which has been successfully decoded toconstitute a DCT block. The data is subjected to the inverse DCT. In thecase of the I picture, an output of the adder 138 is passed through. Inthe case of the P picture, the picture is corrected by the motion vectorportion within the I picture of the reference to be added. The readingof the image memory 137 is controlled and added by the adder 138 so thatthe data is corrected by the motion vector portion.

Further, the DCT mode and the prediction mode motion vector arecontrolled by decoding the header code. In this manner, the datasubjected to the motion vector prediction is decoded and stored in theimage memory 137 to constitute the picture in the original order of theconstitution of the GOP. The inverse scan converter 139 buffers the datato convert the data from the block scan to the raster scan. Further, theswitch 134 is not connected to insert a zero at the time of the normalplayback to perform connecting operation to play back only the playbackdata.

Next, an operation of FIG. 80 will be explained. FIG. 80 is a viewshowing a signal processing block in the case where the data is dividedwith the resolution of the digital signal playback part, the view beinga block diagram explaining an embodiment with respect to the playbackprocessing in the case, in particular, where the aforementioned rateinformation is collected at several places on the disc. The optical headand the rotation of the optical head is controlled so that the data isdirectly or indirectly (rate information description address designated)read from the TOC region or a region corresponding to the TOC region atthe beginning of the disc playback, and the playback signal from theoptical head is amplified by the playback amplifier 156. This signal isdetected with a digital demodulator 157 to be differentiated into thedigital signal for digital demodulation.

Consequently, the playback signal which has become digital data isinputted to the error corrector 158 in which an error included in theplayback signal is corrected. The data free from errors is separatedinto audio bitstreams and video bitstreams by the system layer processor159, and other data items are processed as well. For example, by judgingwhether the signal is video audio data, text data or binary data ofprograms or the like, the stream channel is cut and classified. Out ofsuch data, the aforementioned rate information is stored in the ratedata memory 160.

In the meantime, information is generated by the GOP number counter 161as to which number of the GOP is desired to be processed, and theaddress is calculated by the GOP address calculator 154 to control theoptical head actuator and the rotation speed of the disc. In thismanner, the address of the GOP to be accessed at the time of the skipplayback is searched for by skipping on the disc. When the desired GOPis accessed, the next address is calculated in the same manner and atthe same time the data of the low frequency region obtained by using thestructure described, for example, in embodiment 15 is played back torepresent the data in one screen.

A mode signal indicative of the state such that the skip search is beingperformed or a normal continuous playback is being performed is inputtedto the mode switcher 130 from a microcomputer or the like. The videobitstream is extracted and inputted to the multiplexer 142. Themultiplexer 142 sends the low resolution component data to the secondvariable-length decoder 145 while sending other data items to the firstvariable-length decoder 144 via the switch 143. The switch 143 iscontrolled with the mode switcher 130. Despite that only the playbackpicture output of the low resolution component is demanded as a mode inskip search or the like, the switch 143 is operated so as to be turnedoff in the case where the resolution residual component is played backhalfways. Further, when a playback operation is performed in which agood signal transmission quality is attained in such cases as the normalplayback, the switch 143 is turned on.

The second variable-length decoder 145 decodes a Huffman code and arun-length code. The data is subjected to inverse quantization by thesecond inverse quantizer 147 to be converted from a frequency region tothe space region by the inverse DCT circuit 136. When the data is the Ipicture, the data passes through the adder 149 to be stored in the imagememory. When the data is the P picture, the P picture is referred tofrom the image memory followed by being corrected in position by themotion vector portion to be read to decode the motion compensationprediction by the adder 149. When the data is the B picture, the sameoperation is performed with respect to the I picture and the P picture.

In FIG. 80, the motion vector, the quantization parameter for theinverse quantization, and the prediction mode are outputted from thevariable length decoder. Since the flow of information is the same asFIG. 74, an explanation thereof is omitted. A loop on the low side ofFIG. 75 is the decoding of the low resolution component. The decodingresult is subjected to pixel interpolation by the resolution inverseconverter 152 to compensate for the decoding result as the resolutionresidual difference, the data is inputted to the image memory 150.

Embodiment 20

Next, embodiment 20 of the present invention will be explained withreference to FIG. 81, FIG. 82 and FIG. 83. FIG. 81 is a block diagramfor coding process. FIG. 82 is a block diagram for decoding process. InFIGS. 81 and 82, reference numeral 162 denotes a video signal encoder asencoding means. 163 an audio signal encoder, 164 and 167 memories, 165and 168 memory controllers. The memory 164 and the memory controller 168constitute a data supplying means. Further, the video signal encoder 162and the memory controller 185 constitute a code amount comparing means.Reference numeral 166 denotes a system layer bitstream generator.Reference numeral 169 denotes a variable-length decoder and 170 adecoded signal processor after the variable-length decoder. Thevariable-length decoder 169 and the decoded signal processor 170 serveas a data decoding means. The data rearranger 131 of FIG. 82 serves as adata reconstructing means.

In the beginning, an operation of a structure shown in FIG. 81 will beexplained. Between the video signal encoder 162 and the system bitstreamgenerator 166, the memory 164 is arranged. After the data is embeddedbetween each of the GOPs of coded video signals, each of the GOPs isinputted to the system layer bitstream generator 166 while the audiosignal is coded with the audio signal encoder 163 followed by beinginputted to the system bitstream generator 166 along with a video signalto be subjected to an operation of adding headers or the like.

Here, data embedding operation in the memory 164 will be described. Thememory controller 165 serves as a control circuit of the memory 164 tocontrol the coded video signal controls video signal data so as to embedthe space between each of the GOPs. A signal processing will beexplained by referring to FIG. 83 hereinbelow. FIG. 83 is a viewillustrating a concept of processing at the digital video signal recordand playback device. For example, in the case where (n+1)GOP endhalfways with respect to an access position of an optical head or acontrol unit of an error correction to generate a space of a data regionwhen nGOP generates superfluous data with respect to the access positionof the optical head and the control unit of an error control, the deviceof the invention is controlled so that, as shown in FIG. 83A, thesuperfluous nGOP data is embedded in a space part after (n+1)GOP, and inthe same manner a little amount of residual data of (n+1)GOP whichcannot be embedded in the space because nGOP is embedded and (n+2)GOPare embedded in a space part of (n+3)GOP (the data is embedded in adirection from the left to the right on the paper).

Further, as another method of control, the superfluous data is not sentin the backward direction as described above. As shown in FIG. 83B, when(n+2)GOP exceeds the access position a little so that the (n+3)GOP endshalfways with respect to the access position of the optical head and thecontrol unit of the error control, the device of the present inventionis controlled so that the superfluous (n+3)GOP data is embedded in thespace part after the (n+2)GOP data, and in the same manners the residualdata of (n+2)GOP which cannot be embedded because (n+3)GOP is embeddedis embedded in the space part of (n+1)GOP and (n+1)GOP which cannot beembedded is embedded in the space part of nGOP (in the embeddingdirection from the right to the left on the paper).

Next, an operation of a structure shown in FIG. 82 will be explained.The memory 167 is controlled by the memory controller 168 so that thedata rearranged in accordance with the rule described with respect tothe aforementioned FIGS. 83A and 83B is restored to the original state.For example, in the case where the data shown in FIG. 83A is restored,the device of the invention is operated so that the GOP data is restoredto the original state such that nGOP portion which follows (n+1)GOP isconnected to a part after nGOP data on the left side of the paperfollowed by connecting (n+1)GOP data thereafter and then connecting(n+1)GOP data following the (n+2)GOP data.

This rearranging rule is required to be defined in advance as aformatting rule of a medium so that the rule is recorded as flaginformation in a well-organized region following, for example, the TOCregion. In the case where the rule is not defined, the rule must beclearly described somewhere on the medium.

Embodiment 21

Next, embodiment 21 will be explained by referring to FIG. 84, FIG. 85and FIG. 86. FIG. 84 is a block diagram representing a signal processingunit in the case where the division by the frequency at the digitalsignal playback part is performed, or the division by the quantizationis performed. FIG. 85 is a block diagram representing a signalprocessing unit in the case where the division by the bit length at thedigital signal playback part is performed, or the division by thequantization is performed. FIG. 86 is a block diagram representing asignal processing unit in the case where the division by the resolutionat the digital signal playback unit is performed, or the division by thequantization is performed. In FIGS. 84, 85 and 86, reference numeral 171denotes an IP selection indicator, 172 a decodable determiner and 173 aswitch. In FIG. 86, corresponding parts are shown as an example of thefirst decoding means, the second decoding means and the third decodingmeans. Like parts or corresponding parts in FIGS. 84, 85 and 86 aredenoted by like numerals, and an explanation thereof will be omitted.

Next, an operation of embodiment 21 will be explained. In FIGS. 84 and85, an optical head or the rotation of the optical head are controlledso that the data is read directly or indirectly (the rate informationdescribed address being designated) from a TOC region or a regioncorresponding to the TOC region. A playback signal from the optical headis amplified by the playback amplifier 156. This signal is detected bythe digital demodulator 157 to be differentiated into a digital signalfor digital demodulation. Consequently, the playback signal which hasbecome digital data is inputted to the error corrector 158 to correct anerror included in the playback signal. The data free from errors isseparated into audio bitstreams, and video bitstreams by the systemlayer processor 159 and other data items are processed as well. In FIGS.84, 85 and 86, a control signal is inputted into the IP selectionindicator 171 from the mode switcher 130 as a mode switching means forswitching the decoding means on the basis of the special playback speed.Embodiment 21 is controlled so that the-embodiment 21 is switched overbetween a mode of displaying only the I picture or a mode of displayingthe I picture and the P picture with this control signal and the skipsearch speed.

When skip search speed is 100 times, the GOP must be outputted with aconsiderable thinning if both the I picture and the P picture areoutputted on the screen. Consequently, the picture seems quite unnaturalwith respect to the movement of the played back screen. In such a case,to remove the unnaturalness, the mode is required to be switched to amode of playing back only the I picture. The decodable determiner 132(172 in FIG. 86) is designated to suspend the decoding of not only the Bpicture but also the P picture (the switch 173 serves for this functionin FIG. 86). At the same time, the image memory 137 (150 and 151 in FIG.86) is controlled to display only the I picture.

The screen display of the I picture and the P picture is normallyfavorable up to a speed of 15 times speed, but the screen display ofonly the I picture is more favorable at a speed of 15 times speed ormore. That is because when the whole I picture and the whole P pictureare displayed at a speed of 15 times speed, the continuity of the motionis extremely deteriorated since the GOP which can be played back in thesubsequent process is located at a place of the 5th GOP from the GOPcurrently displayed even if the screen is renewed for each frame.Further, when number of frames in the GOP is N=15 and the I picture andthe P picture has a cycle of M=3, the all the P pictures are decoded butonly the I picture and the second frame of the P picture (third and theninth frame in the GOP) are outputted, much finer skip search can beperformed.

As described above, the data state is divided and recorded by dividingthe data state on the basis of the predetermined condition of thefollowing cases such as a case where the data is recorded by dividingthe frequency region to a predetermined position of each GOP read fromthe recording medium for recording data, a case where the data isrecorded by dividing the data by the resolution, and a case in which thedata is divided by the quantization level to be recorded. Then when thefirst data which is the basic data in the playback data and the seconddata excluding the basic first data is played back from datacollectively arranged, a decoding means is provided to obtain one of theplayback pictures out of the following cases; a case in which all thefirst and the second data is decoded, and a case in which a playbackpicture is obtained which corresponds to the low-frequency region of theI picture and P picture or the number of thinned pixels. Then, thedecoding means to be used at the time of the special playback may beswitched on the basis of the special playback speed.

It goes without saying that the setting of the way of displaying the Ipicture and the P picture may be changed at the time of the playback inthe positive direction and at the time of the playback in the negativedirection. Since the P picture can be decoded only in the positivedirection of time, it is necessary to store screens which exist beforethe P picture to be decoded at the time of the reverse directionplayback. Consequently, it is necessary to use superfluous memory forthat portion. To facilitate the reverse direction playback without usingsuch superfluous memory, the I picture and the P picture may be playedback at the time of the skip search in the positive direction and onlythe I picture is played back at the time of the reverse direction skipsearch.

Embodiment 22

Embodiment 22 will be explained on the basis of FIGS. 87, 88, 89 and 90.FIG. 87 is a block diagram showing a signal processing unit in the casewhere the division by the frequency at the digital signal playback partis performed, or the division by the quantization is performed. FIG. 88is a block diagram showing a signal processing unit in the case wherethe division by the bit length at the digital signal playback unit isperformed. FIG. 89 is a view explaining a concept of processing at thetime of the skip search. In FIGS. 87 and 88, reference numeral 174denotes a field display controller. A system layer processor 159 servesas a video data extracting means. Further, FIGS. 87 and 88 showscorresponding parts as one example of video data decoding and playbackmeans. Reference numeral 130 denotes a mode switcher as a mode switchingmeans. Like parts or corresponding parts are denoted by like numerals inthe aforementioned embodiments in the drawings.

Next, an operation of embodiment 22 will be explained. In FIGS. 87 and88, an optical head and the rotation of the optical disc are controlledso that the data is directly or indirectly (the rate informationdescribed address being designated) read from a TOC region or a regioncorresponding to the TOC region. A playback signal from the optical headis amplified by the playback amplifier 156. This signal is detected by adigital demodulator 157 to be differentiated into a digital signal fordigital demodulating. Consequently, the playback signal which has becomedigital data is inputted to the error corrector 158 to correct an errorincluded in the playback signal. The data free from errors is separatedinto audio bitstreams, and video bitstreams by the system layerprocessor 159 and other data items are processed as well.

When, for example, the I picture and the P picture are continuouslyoutputted to the screen at the time of the skip search, the screen isoutputted in the order denoted by arrows shown in FIG. 89. At this time,the even-field of the I picture and the odd-field of the P picture arecontinuous at the time of the skip search whereas there are four vacantfields between them in the encode data. In other words, the playbackspeed in encode data is five times as fast as the playback speed in thespace between the odd-field and the even-field of the I picture.Therefore, the motion of the I picture varies in an unnatural manner dueto the change in the playback speed from one time speed to five timesspeed for each field.

This is replaced on the same screen as the odd field or the even fieldof the I picture. Otherwise, a screen is prepared by embedding theaverage of the upper and lower scan lines in consideration of theinterlace for output. The image memory 137 shown in FIGS. 87 and 88 iscontrolled by using the field display controller 174 so as to constitutethe same screen in the subsequent P picture. Consequently, a skip amountbetween fields which is a space between fields coded at the time ofrecording data on each field of the picture which is played back can beuniformly obtained with the result that the jerkiness (unnatural motion)becomes inconspicuous.

Further, FIG. 90 is a view explaining a concept of processing at thetime of the reverse playback, a view particularly showing a field orderat the time of the reverse playback. Hereinafter, a field order at thetime of the reverse playback will be explained on the basis of FIG. 90.At the time of the reverse playback, the reverse playback is performedin the unit of frame constituting a pair of the odd field and the evenfield. Specifically, when the operation moves from the odd number fieldto the even number field, the playback is performed in the samedirection as time on the image (a playback operation in which theprocess a is traced in FIG. 90). When the operation moves from the evennumber field to the odd number field, the two field portion is reverselysent in a direction reverse to time on the image (a skip operation inwhich the process b is traced in FIG. 90A).

However, when the aforementioned playback process is taken, a threetimes speed playback is provided with the result that a playback pictureis provided which moves in an awkward manner to see so that the order ofmotion can not be felt smoothly. When the image memory 137 is controlledby the field display controller 174 in FIGS. 87 and 88 so that theplayback picture is displayed in the reverse direction one screen afteranother in the unit of field in the order of odd number, even number,odd number and even number as shown in FIG. 90B. Then since the skipamount between the fields can be almost uniformly obtained, thejerkiness becomes inconspicuous. However, with respect to thesynchronous signal at this time, a normal odd number and even numberfield relation is required to be maintained without inverting the fieldsynchronization signal.

The image memory 137 does not receive the output of the adder 138 as itis to take a display method independent for each of the fields, but theoutput of the adder 138 is received independently from the image memory137. To perform such an operation, the order may be changed by providinga buffer as a separate device. A memory may be used which has threeports in which an address control may be set independently. Theaforementioned operation can be realized even when the data ismultiplexed with a memory which can be operated at a very fast operationspeed to read the data. Further, since the inverse scan converter 139provides at least a memory of at least one field plus one splice, itgoes without saying that such buffering function may be incorporated inthe inverse scan converter 139.

Further, with respect to the slow playback out of the special playback,the jerkiness becomes conspicuous when the same frame is outputtedrepetitively. Consequently, the frame is reconstituted and outputted sothat the playback interval becomes equal. For example, in the case ofthe slow playback at 1/3 times speed, it does not happen that, forexample, after decoded I frame is outputted three times, the decoded Bframe is outputted three times. Instead, the first one frame isconstituted of an odd number field of the I frame. On the even numberfield side, the average of the upper and the lower lines may be taken.

In such a constitution, no picture shift appears in the verticaldirection of the screen due to line shifts in the interlaced picture sothat a stable picture can be obtained. The subsequent one frame outputsthe original I frame, and the subsequent one frame constitutes one framewith the odd number field of the I frame (on the even number field side,the average of the upper and lower lines may be taken). Then thesubsequent one frame outputs the original B frame, and the subsequentone frame constitutes one frame with an even number field of the B frame(on the odd number field side the average of the upper and lower linesmay be taken). Consequently, a slow playback can be realized at an equalinterval in terms of time.

As this invention may be embodied in several forms without departingfrom the spirit of essential characteristics thereof, the presentembodiments are therefore illustrative and not restrictive, since thescope of the invention is defined by the appended claims rather than bythe description preceding them, and all changes that fall within themetes and bounds of the claims, or equivalence of such metes and boundsthereof are therefore intended to be embraced by the claims.

1. A method for recording, on a storage medium, digital videoinformation obtained by coding a digital video signal using motioncompensation prediction, said digital video information comprisingintra-coded I-picture data, predictive-coded P-picture data andbidirectionally predictive-coded B-picture data: said digital videoinformation comprising video data units, each of said video data unitscomprising a sequence of said I-picture data, said P-picture data andsaid B-picture data, wherein each of said video data units has a controldata packet containing control information for reproducing said digitalvideo information, said control packet preceding I-picture data of acorresponding video data unit, wherein said control information includesaddress information of said I-picture data and P-picture data in saidvideo data unit, wherein a reproducing apparatus accesses said controldata packet during playback operation and uses said control informationincluded in said control data packet for reproducing said digital videoinformation.
 2. An apparatus for reproducing digital video informationcontained in a storage medium created according to the method of claim1, wherein said control information is used to reproduce said digitalvideo information.
 3. A method for reproducing digital video informationcontained in a storage medium created according to the method of claim1, wherein said control information is used to reproduce said digitalvideo information.
 4. An apparatus for reproducing digital videoinformation contained in a storage medium created according to themethod of claim 1, wherein said control information is used to reproducesaid digital video information.
 5. An apparatus for reproducing digitalvideo information contained in a storage medium created according to themethod of claim 1, which performs speed play by accessing I-picture databased on said control information.
 6. A method for recording digitalvideo information on a storage medium, said digital video informationbeing obtained by coding a digital video signal using motioncompensation prediction, said digital video information comprisingintra-coded I-picture data, predictive-coded P-picture data andbidirectionally predictive-coded B-pictured data, said methodcomprising: forming video data units, each of said video data unitscomprising a sequence of said I-picture data, said P-picture data andsaid B-picture data, creating a control data packet containing controlinformation for reproducing said digital video information, said controlinformation including address information of said I-picture data andP-picture data, said control packet preceding I-picture data of acorresponding video data unit, forming a system stream comprising saidvideo data units, each of said video data units having said controldata, and recording said system stream on said storage medium.
 7. Anapparatus for reproducing digital video information contained in astorage medium containing digital video information recorded by a methodaccording to claim 6, wherein said reproducing apparatus accesses saidcontrol data packet during playback operation and uses said controlinformation included in said control data packet for reproducing saiddigital video information.
 8. A method for recording, on a storagemedium, digital video information obtained by coding a digital videosignal using motion compensation prediction, said digital videoinformation comprising intra-coded I-picture data, predictive-codedP-picture data and bidirectionally predictive-coded B-picture data: saiddigital video information comprising video data units, each of saidvideo data units comprising a sequence of said I-picture data, saidP-picture data and said B-picture data, wherein each of said video dataunits has a control information for reproducing said digital videoinformation, said control information preceding I-picture data of acorresponding video data unit, wherein said control information includespicture arrangement information of said I-picture data and a P-picturedata and B-picture data in said video data unit, wherein a reproducingapparatus accesses said control information during playback operationand uses said control information for reproducing said digital videoinformation.